Everton manager Roberto Martinez feels Romelu Lukaku's World Cup exertions may see him miss their Premier League opener.
Lukaku joined Everton from Chelsea 10 days ago in a club-record deal worth £28million after a successful loan spell on Merseyside last season.
The Belgium international scored 16 goals last term, helping Everton to a fifth-place finish in Martinez's maiden season in charge.
He then scored in Belgium's 2-1 last-16 win over the United States at the World Cup as Marc Wilmots' men reached the quarter-finals in Brazil.
And, ahead of Everton's opening-day trip to Premier League new boys Leicester City next Saturday, Martinez is wary of risking the 21-year-old former Anderlecht man.
"When you have players coming back from the World Cup you have to decide if you want the players straight away or do you give them a bit of time to refresh and be ready to play for 10 months?" Martinez said.
"It will only be [Belgium winger] Kevin Mirallas and Rom who might not start the season. For Romelu, it will depend on how he adapts to work from now until August 16.
"There is a degree of risk if you put them into a situation so early. They've been training really well and are accumulating a lot of work."
Aside from Lukaku, defender Muhamed Besic and midfielder Gareth Barry have been among those to arrive at Goodison Park in the close season.
Martinez is willing to dip into the transfer market again, but stressed that Everton's remaining business will depend on the fitness of Arouna Kone and Bryan Oviedo - both of whom are recovering from long-term injuries.
"Towards the end of last season I said we needed six more players, but it wasn't six new players, it was six players," Martinez added.
"We have added Barry, Lukaku and Besic and we also have [full-back] Tony Hibbert who re-signed.
"We still need one or two, depending on how quickly Arouna Kone and Bryan Oviedo recover from their injuries."
|Toure keen to bounce back from ´disappointing´ campaign|
|El Salvador v Canada: Floro targets Gold Cup learning curve|
|Juve complete Zaza swoop|
|Costa Rica v Jamaica: Borges confident Wanchope´s men are ready|
|Marseille snare Sarr|
|Italy coach Conte to stand trial in match-fixing case|
|Castan keen to repay Roma´s faith|
|Rami thrilled to reunite with ´best coach´ Emery at Sevilla|
|Lusitans v West Ham: Tomkins seeks to silence minnows|
|Kagawa shines as Dortmund hit six in Japan|
|Alonso tips Gerrard for Galaxy glory|
|Firmino seeks self-improvement with Liverpool|
|Buffon bids farewell to Pirlo|
|Sterling named Europe´s ´most valuable´ young player|
|Casillas´ agent reveals Porto offer|
|Southampton bring in Martina|
|Dundee United accept Celtic´s Ciftci bid|
|McArthur pens new Palace deal|
|Bartomeu rules out Barca move for Pogba this year|
|Spurs have to be better now - Bentaleb|
|Milner expects central role|
|Micronesia thrashed again, this time 46-0|
|Marchisio: I cannot be Pirlo´s heir|
|Inter aiming for Champions League return - Icardi|
|UEFA Europa League Preview: Brondby and Slovan to protect handsome leads|
|Bentaleb pens new long-term deal at Tottenham|
|Barca agree Turan deal|
|FIFA bans Mayne-Nicholls|
|United States v Honduras: Klinsmann demands improvement ahead of Gold Cup opener|
|CONCACAF institutes extensive reforms in wake of FIFA corruption scandal|
|Mauri completes Milan move|
|City sign Turkey striker|
|Women´s World Cup final draws huge US TV ratings|
|My first Chelsea team better than current crop - Drogba|
|Bertrand set for lay-off after knee surgery|
|New five-year Juve deal for Marchisio|
|Allegri extends Juve contract|
|Koeman reiterates Alderweireld interest|
|Valencia bag Bakkali|
|New York City FC complete Pirlo capture|
|Panama v Haiti: Collat ready to challenge the best of CONCACAF|
|UEFA Champions League Preview: Harrison eyes TNS progression|
|FIFA sanctions Yemen for fielding ineligible player|
|Toulouse rubbish Ben Yedder exit reports|
|Mourinho ´knows what he´s doing´ with Falcao signing|
|Watford shell out club-record fee for Capoue|
|Braafheid signs Lazio extension|
|Nani finalises Fenerbahce move|
|Liverpool confirm O´Driscoll appointment|
|Liverpool have to start better - Lucas|
|USA simply too good - Sasaki|
|Portland Timbers 1 San Jose Earthquakes 0: Jewsbury wins it in stoppage time|
|No move yet for Van Persie|
|Lloyd wins Golden Ball, Silver Boot awards|
|Mascherano: I never grabbed Banega|
|Dunga requested Brazil not appeal Neymar´s suspension|
|United States 5 Japan 2: Lloyd stars with hat-trick|
|Fiorentina deny Inter criticism|
|Nani relishing Fenerbahce opportunity|
|Newcastle hold talks over Northampton youngster|
|Cuadrado´s agent plays down Chelsea exit rumours|
|Liverpool´s Alberto set for Deportivo loan|
|Leverkusen suffer surprise defeat, Stuttgart hit six|
|Inter ´dismayed´ at Fiorentina vice-president´s Salah Twitter outburst|
|Blaszczykowski ruled out of Dortmund´s Asia tour|
|Gerrard gets the beers in for LA Galaxy fans|
|De Gea coy over Real links|
|Former Brazil star Carlos handed Delhi reins|
|Ciftci will not push through Celtic switch – agent|
|In-demand Mitrovic considering Roma offer|
|Lehmann calls on Cech to ´get over´ Chelsea|
|Marlos double sinks Monaco|
|Mauritius 0 South Africa 2 (agg 0-5): Bafana set up Angola qualifier|
|Keane relishing Gerrard arrival|
|Palace confirm Cabaye interest|
|Hamburg bring in Spahic after head-butt ban|
|Blatter hits out at France and Germany over World Cup votes|
|Sanchez: World Cup exit spurred Chile to Copa glory|
|Jojic makes Cologne switch, Santana move falls through|
|Carrillo keen to get going at Monaco|
|Micronesia thrashed 38-0 as Fiji triumph in Olympic qualifier|
|Schalke stunned by ´machine´ Caicara|
|MLS Review: Keane shines at Gerrard´s Galaxy unveiling|
|Counter-attacking the key for Japan|
|Jimenez happy at Atletico|
|Gerrard predicts ´successful future´ with Galaxy|
|Iniesta can´t see Real selling Ramos|
|Keshi sacked as Nigeria coach|
|Three finals, three defeats for Messi, Mascherano|
|Nani close to Fenerbahce move|
|Sampaoli revels in ´unbelievable joy´|
|Bravo: Copa victory a dream|
|Martino: Argentina should have won|
|Chile 0 Argentina 0 (4-1 on penalties): Hosts end trophy drought|
|Germany 0 England 1 (after extra time): England make World Cup history|