Jackson Martinez scored his first UEFA Europa League goal as Porto defeated Napoli 1-0 in the first leg of their last-16 clash.
Porto dominated for large parts of Thursday's game, but a combination of an incorrect offside decision that ruled out Carlos Eduardo's effort and the outstanding Pepe Reina frustrated them.
There was nothing Reina could do, though, to stop Martinez netting the only goal at the Estadio do Dragao after he reacted quickest to sweep home from 12 yards.
Martinez's 23rd goal of the season in all competitions means Porto travel to Italy for the second leg next week with high hopes of reaching the quarter-finals.
Porto ended a four-game winless run in all competitions at the weekend with a confidence-boosting 4-1 victory over Arouca and bossed the first half against Napoli with ease.
In what was the first European game in charge for interim coach Luis Castro, Porto would have been ahead early on but for a remarkable save from Reina.
Eduardo chipped a delightful ball to Martinez and he met it sweetly on the half-volley, but Reina showed great reflexes to tip away the shot.
The 2010-11 Europa League winners continued to have the best of proceedings, with Steven Defour next to sting the palms of Reina.
Castro's men should have been in front after 19 minutes when Martinez's inviting cross was nodded in by Eduardo, only for it to be incorrectly ruled offside.
The pattern of dominance continued in the early exchanges of the second half when Reina produced another superb stop to acrobatically claw away Fernando's rasping 30-yard drive.
Ricardo Quaresma scored two goals at the weekend and impressed again but his 50th-minute strike drifted wide.
Rafael Benitez is aiming to become the first manager to win the competition with three different clubs and his side finally showed some attacking intent after 52 minutes.
Napoli broke the offside trap and Jose Callejon set up Gonzalo Higuain, whose shot was low and powerful but went through Helton's legs and squirmed wide.
The Porto goalkeeper was in action again when Raul Albiol was left unmarked from a corner, but his low header was kept out by the feet of the Brazilian.
Helton brilliantly denied Higuain and the ball fell to Callejon six yards out, but he could not sort his feet out.
But the game swung Porto's way after 57 minutes when a corner was only half-cleared and Martinez showed great technique 12 yards out to lash home via a deflection.
It somehow stayed as 1-0 to the hosts with nine minutes remaining when Miguel Britos made a last-ditch tackle and his clearance from the floor cannoned straight off Juan Quintero and onto the post.
|Coach: Luís Castro|
for Carlos Eduardo 67'
for Silvestre Varela 72'
for S. Defour 87'
|Klopp hails Kagawa, expresses Kehl concern|
|Wenger pleased with wonderful Welbeck|
|Juanfran warns Atleti after Juve win|
|Ronaldo injury not serious, says Ancelotti|
|Rodgers left to rue another Liverpool set-piece slip-up|
|Chiellini holds regrets over Atletico defeat|
|Atletico Madrid 1 Juventus 0: Turan winner ends Juve streak|
|Malmo 2 Olympiacos 0: Rosenberg´s brace creates history for hosts|
|La Liga Preview: Bilbao face uphill task at Real, Valencia host Atletico|
|Arsenal 4 Galatasaray 1: Welbeck treble ensures happy anniversary for Wenger|
|Bayer Leverkusen 3 Benfica 1: Son inspires dominant Leverkusen|
|Ludogorets 1 Real Madrid 2: Benzema spares blushes for visitors|
|Basel 1 Liverpool 0: Streller strike gives Swiss side victory|
|Anderlecht 0 Borussia Dortmund 3: Immobile, Ramos help Germans cruise|
|Berbatov could miss PSG clash|
|Hamsik looking forward to ´special´ Slovan homecoming|
|League Two Preview:Debt-free Portsmouth in party mood|
|Villas-Boas critical of Zenit performance|
|Eredivisie Preview: Amsterdam giants out to avenge humiliation|
|Ligue 1 Preview: Stuttering title favourites face off in Paris|
|Martinez does homework on Krasnodar|
|Zenit 0 Monaco 0: Hosts held to dour draw|
|Pochettino backs Adebayor to find form|
|Pazzini relaxed over Milan progress|
|Ramsey and Allen to miss Wales qualifiers|
|Icardi open to new Inter contract|
|Mazzarri wants Inter perspective|
|Ideye close to Albion return|
|Ogunode doubles up in Incheon|
|K. League Review: Jeonbuk extend lead as Pohang lose|
|Western Sydney Wanderers 2-0 Seoul (agg 2-0): Poljak and Cole fire Australians to final|
|Zamora impressed by Vargas|
|Benteke return has boosted Villa – Weimann|
|Muniesa determined to keep starting spot|
|Diaby prepared to adapt|
|Players to blame, not Pardew - Williamson|
|Dyche looking for squad to step up|
|Havenaar and Kagawa earn Japan recalls|
|Relieved Terry glad to bounce back|
|Martinez backs Besic to shine|
|We paid dearly - Iniesta|
|Blanc hails PSG spirit|
|Tempo not good enough for Milner|
|Rodgers: Sturridge not fit for England|
|Prandelli urges daring approach|
|Jesus bullish ahead of Leverkusen match|
|Bundesliga Preview: Hamburg´s task gets no easier, Bayern battle Hannover|
|Hummels committed to Dortmund|
|Sao Paulo 1 Huachipato 0: Brazilians claim first-leg honours|
|Premier League superior to Serie A - Isla|
|Ferdinand taunts stay-away City fans|
|Simundza hails Maribor effort|
|Yermakovich overjoyed with BATE win|
|We targeted Ajax in the air - Donis|
|Gago among three Argentina inclusions|
|Pellegrini rues poor City showing|
|Aduriz admits Bilbao not good enough|
|Lucescu can´t hide Shakhtar despair|
|De Boer frustrated at ´nothing´ penalty|
|Winning margin not important - Mourinho|
|Maicon disappointed at dropping points|
|Luis Enrique upbeat despite defeat|
|Draw would have been fair - Silva|
|Record-breaker Totti rues Manchester misses|
|Keller: My Schalke players are shattered|
|Championship Review: Norwich beaten, McKinlay off to winning start|
|Champions League centurion Terry proud of achievement|
|Luiz hopes Barca win can kickstart PSG season|
|Crewe Alexandra 0 Notts County 3: Cassidy brace sinks basement boys|
|Aberdeen 2 St Mirren 2: Struggling visitors fight back|
|Shakhtar Donetsk 2 Porto 2: Martinez´s late double salvages dramatic draw|
|Slutsky shrugs off possession statistic|
|Manchester City 1 Roma 1: Evergreen Totti pegs back City|
|APOEL 1 Ajax 1: Manduca rescues point for hosts|
|Schalke 1 Maribor 1: Slovenian underdogs hold firm in Germany|
|BATE 2 Athletic Bilbao 1: Hosts secure first victory over Spanish side|
|Paris Saint-Germain 3 Barcelona 2: Luis Enrique tastes defeat as Xavi makes history|
|Sporting Lisbon 0 Chelsea 1: Matic returns to haunt old rivals|
|K. League Preview: Jeonbuk´s leadership under threat|
|Inter v Qarabag: Mazzarri looking for response|
|Guardiola unimpressed by empty Arena Khimki|
|Krasnodar v Everton: Martinez´s men may be handed triple boost|
|Arabian Gulf League Review: Al Wahda held, Al Shabab win again|
|Schmidt: Leverkusen must match Benfica aggression|
|CSKA Moscow 0 Bayern Munich 1: Century up for German giants|
|Al Ain 2 Al Hilal 1 (agg 2-4): Saudis make final as Gyan sees red|
|Romulo sidelined following hernia surgery|
|Sturridge to miss Basle clash|
|Everton pessimistic over Mirallas injury|
|UEFA Europa League Preview: Mazzarri demands Inter fight, Hecking eyes improvement|
|Ancelotti: Ronaldo an example for everyone|
|Evans returns to Northern Ireland squad|
|Simeone earmarks ´extraordinary´ Tevez as Juve´s dangerman|
|Kitchee 1 Erbil 2 (agg 2-3): Early goals see visitors through|
|Herrera sustains fractured rib|
|Tottenham v Besiktas: Kaboul calling for more of the same|
|Scotland call up debutants Gauld and May|
|Ramsey out for up to four weeks|
|Giroud deal done - Wenger|
|Hull City challenge FA over name change ruling|
|Rooney impressed with McNair|
|Luiz: I nearly joined Barca|
|Persipura 0 Al Qadsia 6 (agg 2-10): Visitors coast into final|
|Blanc wary of ´exceptional´ Messi|
|Dawson extends Albion deal|
|Mourinho open to move within Premier League|
|Top four the priority - Van Persie|
|Liga MX Preview: Queretaro braced for Atlas challenge|
|Copa Sudamericana Preview: Sao Paulo out to arrest slump|
|MLS Preview: DC United ready to grind, Revolution host Crew|
|Argentine Primera Division Review: Newell´s unbeaten run ends|
|Mignolet shrugs Valdes, Liverpool link|
|Neville blames transfers for Newcastle form|
|Mathieu applauds Messi, Neymar partnership|
|Mignolet must improve - Carragher|
|Cole hails Lampard|
|Villa may miss opener in Australia|
|Hughes thrilled with ´deserved´ home win|
|Pardew fears for future|