Frank Lampard should learn tomorrow whether he will miss Chelsea's top-of-the-table Barclays Premier League showdown with Manchester United after he lasted just 15 minutes of their first serious defeat of the season.
Lampard limped out of last night's 2-1 Champions League loss at Shakhtar Donetsk with a recurrence of the calf injury that ruled him out of England's World Cup qualifiers against San Marino and Poland and was set to undergo a scan to determine the extent of the problem.
The 34-year-old's withdrawal from yesterday's damaging Group E defeat saw manager Roberto Di Matteo's game-plan go up in smoke, leaving Chelsea in danger of becoming the first holders to crash out of the competition before the knockout phase.
With John Terry resuming his domestic racism ban, vice-captain Lampard's absence against United on Sunday could leave Di Matteo with another headache in a game the Blues will be desperate to win to open up a seven-point gap on their opponents.
Confirming the midfielder would undergo a scan today - the results of which will be revealed tomorrow - Di Matteo said: "It's basically a recurrence of an old injury.
"He was training with us fine and there were no alarm bells before the game. He was in good condition to play."
Di Matteo admitted the loss of Lampard last night threw his masterplan into disarray as Chelsea lost for the first time since their UEFA Super Cup thrashing by Atletico Madrid.
The result also came at a time of the season when the Blues have traditionally suffered a slump, but Di Matteo added: "It's a team that has always shown the character after a defeat and I don't think the previous years should affect the way we are playing this season or where we are this year.
"We are doing everything we can to prevent that as well. The team is in good physical condition and also we have a good squad, so we'll try to utilise everybody that we can."
However, Di Matteo accepted Chelsea must avenge last night's result in two weeks' time and win their final home game against Nordsjaelland if they are to avoid one of the shortest ever defences of the Champions League.
"We need to win our two home games remaining, for sure," he said.
"But certainly, we need to win our home game against Shakhtar."
The Italian warned warned the Ukrainian side that Chelsea would be a different prospect at Stamford Bridge.
"I'm confident, at home, it will be a different game for Shakhtar and we are also very strong at home," he said, denying Chelsea had one eye on the United game but admitting victory on Sunday would be the perfect birthday present for owner Roman Abramovich, who turned 46 today.
Shakhtar boss Mircea Lucescu claimed he knew his side would win and was already looking further ahead than the return match with Chelsea.
"The coming matches against Nordsjaelland and Juventus will be rather important for us," he said.