Chelsea's bid to win a third major European trophy in successive seasons begins when they host Basel in the UEFA Champions League.
The Premier League side won the UEFA Europa League last season, while they lifted the Champions League in the 2011-12 campaign, and they will be determined to claim the main prize again.
Wednesday's Group E clash at Stamford Bridge will be vital for the London club, with returning manager Jose Mourinho sure to demand a fast start from his men.
Chelsea and Basel are well acquainted, having met in the semi-finals of the Europa League last term, with Chelsea winning 5-2 on aggregate.
That success came under interim manager Rafael Benitez, though, with Mourinho in charge now as he looks to win the title for the third time.
Mourinho has won the Champions League at both Porto and Inter, but is yet to win it at Chelsea, coming closest in 2004-05 and 2006-07, when they reached the semi-finals.
Chelsea have not made an ideal start to the season, winning just two of their first four Premier League matches, while they lost to Bayern Munich in the Super Cup final on penalties last month.
As a result, they lie sixth in the Premier League table, with Saturday's 1-0 defeat at Everton fresh in the memory.
Cameroon international Samuel Eto'o made his debut in that fixture, but the 32-year-old striker was guilty of missing several chances.
Mourinho will expect more from the former Inter player, and Spaniard Fernando Torres may start as a result of his sub-standard performance.
Chelsea's array of young stars could all play big roles in the Champions League this season, with Oscar, Eden Hazard and Andre Schurrle all impressing in the early stages of the campaign.
Basel have their own stars to boast and among those is veteran forward Marco Streller, who has already racked up four goals in just five games in the Swiss Super League.
Their league form has been good, losing just one of their seven matches this season, and they sit third on the table as a result.
The Swiss side have form for giant-killing – they essentially knocked Manchester United out of the group stages in the 2011-12 Champions League by beating them on the last matchday of the group stages – and Murat Yakin's side have had to work hard for their spot in this year's competition.
They beat Maccabi Tel Aviv 4-3 on aggregate before toppling Ludogorets 6-2 in the play-off round.
|16||M. van Ginkel||42'|
|Coach: José Mourinho|
for Willian 67'
for F. Lampard 76'
for M. van Ginkel 76'
|Ighalo rejected Chinese fortune for Premier League dream|
|Tuchel inspired by Kerber as Dortmund hunt down Bayern|
|Liverpool chief warns fans: Be careful what you wish for|
|Malaga 3 Getafe 0: Debut goal for Atsu in routine victory|
|Brighton and Hove Albion 3 Brentford 0: Hughton´s side boost promotion hopes|
|Borussia Monchengladbach 5 Werder Bremen 1: Christensen double inspires emphatic win|
|Aguero lauds Vardy ahead of top-two clash|
|Levante v Barcelona: Guardiola record beckons in Luis Enrique´s 100th game in charge|
|Strootman scores on return to action|
|Barcelona respond to Mediapro allegations|
|Frosinone v Juventus: Cuadrado not thinking of Napoli test|
|Herrera fires warning to Guardiola ahead of Manchester City move|
|Chelsea v Manchester United: Hiddink unconcerned by Van Gaal rivalry|
|Granada v Real Madrid: El-Arabi backs revamped hosts to shock Zidane´s men|
|Chelsea won´t take risks with Pato - Hiddink|
|CAF backs Sheikh Salman in FIFA race|
|AFC Bournemouth v Arsenal: Wenger pleased with Afobe success|
|Van Gaal: Beating Chelsea will keep title hopes alive|
|AC Milan v Udinese: In-form Niang wary of distractions|
|Marseille v Paris Saint-Germain: Di Maria relishing Classique experience|
|Simeone shoulders blame for misfit Martinez|
|Welbeck closes on Arsenal comeback|
|Verona v Inter: Icardi out to silence critics|
|Leicester remind Pellegrini of his Villarreal|
|Veteran Weidenfeller extends Dortmund stay|
|Klopp laughs off Sturridge exit rumours|
|Impending Chelsea exit hasn´t affected Terry, claims Hiddink|
|Pellegrini: City did nothing behind my back over Guardiola|
|Fred´s doping ban extended worldwide by FIFA|
|Berahino won´t start against suitors Newcastle - Pulis|
|Guardiola identifies threat from ´intense´ Leverkusen|
|Reus gets green light for Dortmund return|
|Di Maria desperate to banish Manchester United memories|
|Wenger: China a major threat to the Premier League|
|Guardiola: I am like a woman, I can multi-task|
|Alex Teixeira: I wanted Premier League move|
|Adelaide United 2 Sydney FC 2: Cirio double not enough for hosts|
|Rosicky out for two to three months - Wenger|
|Wenger: Arsenal not obsessed with finishing ahead of Tottenham|
|Howe upbeat over Wilson, Gradel recoveries|
|Dani Alves opens up about Ronaldo feud|
|Ljajic wants permanent Inter move|
|Eriksson: Money too good to refuse in China|
|Alex Teixeira completes €50m Jiangsu Suning move|
|McClaren calls for help from injury-hit squad|
|Bilic: New stadium won´t make us world class|
|´Killer´ Aguero gives City edge - Hart|
|Michu: I would love Swansea return|
|Hodgson calls England squad meeting|
|MLS starts stadium site search for possible St. Louis expansion|
|Copa Libertadores Review: Santa Fe cruise in Bolivia|
|Ronaldinho: I would support Neymar if he wanted Madrid move|
|Real Betis confirm Damiao signing|
|Alves: I almost joined Madrid|
|Melbourne City sign Socceroo Wilkinson|
|I´d like to say: ´Yes we can´ - Ranieri channels Obama over title chances|
|New stadium means Spurs in ´very tough´ period - Pochettino|
|Rennes 0 Saint-Etienne 1: Sall good for Galtier´s men|
|Sevilla 4 Celta Vigo 0: Gameiro at the double after penalty failure|
|Shakhtar boss Lucescu: Teixeira set for China move|
|Depay could be the world´s best winger - Kanchelskis|
|United States v Canada: Klinsmann pursues dual goals|
|Tottenham v Watford: Title-chasing Spurs braced for Watford battle|
|Wilmots relaxed over De Bruyne´s Euro 2016 fitness|
|Atletico Madrid v Eibar: Gimenez confident of overcoming defensive headache|
|Filipe Luis has ban for Messi challenge reduced|
|Aston Villa v Norwich City: Garde and Neil demand victory in relegation scrap|
|Zidane adds former team-mate to backroom staff|
|Liverpool v Sunderland: Klopp demands smarter attack as injury comebacks continue|
|Caceres to undergo Achilles surgery|
|´They call me Blackenbauer´ - Monaco clarify Jemerson nickname|
|Hertha Berlin v Borussia Dortmund: Buoyant Brooks believes best is yet to come|
|Swansea City v Crystal Palace: ´Miserable´ Pardew wants end to dismal run|
|Neymar´s father claims Manchester United met buyout clause|
|Lazio punished following racist chants|
|Southampton v West Ham: Bilic wary of ´flying´ Austin|
|Bayer Leverkusen v Bayern Munich: Neuer ready for ´aggressive´ challenge|
|Wilshere: Difficult to stay positive|
|Stoke City v Everton: Imbula debut to boost depleted Potters|
|Manchester City v Leicester City: Ranieri aims to break the magic circle|
|Elber: Lewandowski should reject Real Madrid - and Higuain cannot replace him|
|Neuer denies Bayern rift amid Vidal paper row|
|Kane and Vardy as good as Aguero, says Pochettino|
|McArthur, Puncheon out for ´long period´|
|Patient Gotze plots ´clever´ comeback|
|Newcastle United v West Brom: McClaren demands reaction|
|Villa turn to former governor of the Bank of England|
|I´ll be taking my dog round to bite him - Shinnie plans unorthodox motivation|
|´Traumatic´ changeover hurt Benitez at Madrid - Capello|
|Alderweireld: No heroes at Tottenham|
|Suarez ´certain´ Neymar will stay at Barcelona|
|Barcelona cheers didn´t bother me - Cheryshev|
|Koulibaly lauds referee Irrati for halting Lazio-Napoli game|
|Forget Twitter and focus on football, Foster tells Berahino|
|Ibrahimovic hails PSG depth as champions make Ligue 1 history|
|Furious Canizares demands resignation and apology from Neville|
|Victory rule out Valeri for rest of season|
|Copa Libertadores Review: Puebla, Cesar Vallejo held at home|
|Forster quiet on Euro 2016 chances|
|Luis Enrique sympathises with Valencia plight|
|Afobe: I have nothing to prove against Arsenal|
|Mustafi apologises to Valencia fans for Camp Nou drubbing|
|Blanc demands more from PSG|
|Pioli: Racist fans just a minority|
|Serie A Review: Napoli win but Juve remain two points behind|
|Stuart Holden calls time on injury-marred career|
|Luis Enrique: Barcelona players should be celebrated|
|Suarez just happy to help the team after starring in Copa romp|
|We never doubted Icardi, says Inter´s sporting director|
|Watford boss Flores praises ´fighting´ Costa|
|Allegri delighted as disciplined Juventus prove title mettle|
|Under-fire Neville won´t resign after Camp Nou thrashing|
|McClaren: Newcastle new boys will take time to gel|
|Mihajlovic: Milan possession must have purpose|
|Hiddink accuses Watford players of provoking Costa|