Andre Villas-Boas has admitted Chelsea could be left short of cover in midfield if injury strikes Frank Lampard again this season.
Lampard was sidelined for three-and-a-half months last term, his absence coinciding with the Blues' worst run in the Barclays Premier League for almost 15 years.
The England star returned to help them go close to completing the greatest comeback in Premier League history, but they ultimately came up short and finished the campaign empty-handed.
Chelsea have already lost two midfielders before the start of this season, with Yury Zhirkov returning to Russia and Michael Essien ruled out for six months with a serious knee problem.
The man signed to fill the void, Oriol Romeu, is still on international duty with Spain at the Under-20 World Cup and may not be available for selection until next month.
Chelsea have also made two attempts to prise Luka Modric from Tottenham but so far without success.
And although Villas-Boas is happy with his squad going into his first competitive game in charge against Stoke on Sunday, he acknowledged resources could easily become stretched.
"We are struggling with numbers in midfield," he said.
"We have Oriol still away at the under-20s World Cup.
"He'll return late in August, so numbers are short."
Sunday's game is likely to see Chelsea line up with a three-man midfield of Lampard, Ramires and John Obi Mikel, with Josh McEachran as back-up.
Villas-Boas revealed he would also consider asking Yossi Benayoun or Florent Malouda to play more centrally if necessary.
"It's good enough for us that the people we have can play in those positions - we have a lot of versatility in midfield," he said.
"Florent Malouda and Yossi can play number eight or number 10, and that gives us flexibility.
"That's why we're happy with the squad running into the Stoke game.
"All have been playing at a high level.
"In midfield, everyone has been performing well."
While Chelsea may have a shortage of midfielders, the impending arrival of 18-year-old Romelu Lukaku from Anderlecht would give them a surplus of strikers.
That is where Villas-Boas' first big selection dilemma lies, with one of Didier Drogba and Fernando Torres likely to be left on the bench at the Britannia Stadium.
Chelsea are optimistic Torres will be fit despite having suffered some memory loss after being concussed in Spain's friendly defeat in Italy on Wednesday.
But Drogba is favourite to start having impressed in pre-season, with the Ivorian also seeming better suited to Stoke's physical game.
Daniel Sturridge would almost certainly have lined up on the right side of attack in a 4-3-3 but for a three-match ban picked up in his final game on loan at Bolton last season.
Stoke manager Tony Pulis has ruled out the possibility of defender Matthew Upson making his Potters debut, with the former West Ham defender not yet ready for competitive action, But fellow new signing Jonathan Woodgate could feature.
Pulis is hopeful Rory Delap (hamstring) and Matthew Etherington (rib) will overcome niggles while Ricardo Fuller, Mamady Sidibe and Danny Higginbotham are long-term absentees.
Stoke will begin this Premier League season with the same aim they have had at the start of the previous three - to stay in the top flight.
Since their arrival in the Premier League in 2008, the Potters have gone from relegation favourites to a role model for promoted clubs.
Last season was the best yet, with a comfortable 13th-placed finish and a superb run to the FA Cup final, which brought with it European football.
Stoke have already made their mark in the Europa League, beating Hajduk Split over two legs to register the club's first ever victory in a European tie.
All this has been achieved under the shrewd guidance of Pulis, and he is determined there will be no complacency as they prepare for their opener against Chelsea.
"I think we have to be a little bit careful," said the Welshman. "The expectation levels go through the roof.
"We've had a fantastic run of success. It's been an upward curve now for nearly five years, and that's very unusual at any football club that you keep bettering what you've done year after year.
"I think the great thing about the football club is the supporters have enjoyed it so much but they remember what it's like in the Championship. They understand that our priority is to stay in the Premier League - that will always be the case.
"Yes, we're looking to push on but there are some fantastic clubs and fantastic teams that we have to compete against.
"Managing expectations at football clubs now is almost as difficult as managing the players on the pitch but you learn and you have to get on with it."
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