Christian Pulisic faces a race against time to be fit for the new Premier League season.
Frank Lampard has revealed the United States winger needs six weeks to beat the hamstring injury he suffered in Chelsea's 2-1 FA Cup final defeat to Arsenal.
Pulisic has starred in his first campaign with Chelsea after switching from Borussia Dortmund, with the 21-year-old a particular revelation after the coronavirus lockdown.
With the new Premier League campaign expected to start on September 12, Blues boss Lampard has admitted Pulisic will have an uphill struggle to be ready in time.
"With Christian Pulisic I think it's going to be touch and go for the start of the season," said Lampard.
"We're probably looking around a six-week injury. So with six weeks, doing the maths, it gets very close to, and is probably into, the start of the new season.
"But we have to treat it right, the injury."
Pulisic has racked up 11 goals and eight assists in his maiden campaign at Chelsea, and Lampard hailed the fast-improving forward for such an impactful start to the Stamford Bridge career.
"In the big scheme of things with Christian, when he reflects on his first season, the improvement levels coming here when you think of the goals and assists he's had this year, it's the best of his career," said Lampard.
"And that's his first year in the Premier League.
"From where he's gone at the start to how he's ended up and how he has played in restart, he should be very happy, and that's down to his work.
"So we'll get him fit, and get him ready. If he misses the first one or two games of the season, then we'll have a firing Christian hopefully as hungry as he looked for the restart."
Cesar Azpilicueta also suffered a hamstring complaint in Chelsea's FA Cup final defeat, but the Blues skipper faces a shorter rehab period than Pulisic.
N'Golo Kante and Ruben Loftus-Cheek are both fit to face Bayern Munich in Saturday's last-16 Champions League second leg.
Callum Hudson-Odoi appears primed for a start against Bayern with the Blues 3-0 down from the first leg in March, with Willian still sidelined through ankle trouble and Pedro recovering from shoulder surgery.
Chelsea have also taken academy players Lewis Bate, Henry Lawrence, Dynel Simeu, Ian Maatsen and Armando Broja with them to Munich.
