While Chelsea play Birmingham today trying to recover from its worst home defeat since Roman Abramovich bought the club seven years ago, captain John Terry is on the sidelines worrying about more than whether his team will retain the Premier League title.
Terry will be absent for a second straight match at Birmingham and although central defensive partner Alex will figure despite an ongoing knee problem that still requires surgery, Chelsea's defense looks as vulnerable as it did in last week's 3-0 loss to Sunderland.
Chelsea now lead by just two points and could be overhauled by Arsenal if it loses but Terry is concerned about the long-term implications of his latest injury.
The nerve injury that has caused him pain since the end of last season has finally forced him to seek treatment, but it is just the latest problem to affect the former England captain.
The 29-year-old Terry is now thinking about how his body will hold up when he retires in a few years.
"The last time I played fit? Maybe five years, maybe more, I can't really remember," Terry said. "If you can take an anti-inflammatory and struggle through, you do. The pain from this injury is the worst I have had, there is no way I can continue.
"I'm 30 next month and I've got to start looking after myself."
That could leave Chelsea without its first-choice defender for some time and looking to recruit in the January transfer window. Alex is out for as long as eight weeks with a knee injury.
Terry said before Chelsea's 2008 Champions League final defeat to Manchester United that he did not care if he spent his retirement in a wheelchair so long as he was counting his winner's medals.
His latest setback has made him reconsider.
Chelsea's four-man defense against Sunderland featured three right-backs but Brazil center back Alex should replace either Paulo Ferreira or Jose Bosingwa against Birmingham, which is in the relegation zone but has lost just one of six home matches.
Lee Bowyer could return to Birmingham's midfield if Craig Gardner fails to recover from the ankle injury he sustained in last weekend's 0-0 draw against Manchester City.
Arsenal could overtake Chelsea if the leader loses and the Gunners beat local rival Tottenham.
Andrei Arshavin and Tomas Rosicky are expected to be fit for Arsenal, while Robin van Persie could play after continuing his recovery from an ankle injury with a second-half appearance in the Netherlands' 1-0 friendly win over Turkey on Wednesday.
Tottenham has never won in six visits to Emirates Stadium and its last win at Arsenal came at Highbury in 1993, when the Gunners rested its entire first team in preparation for the FA Cup final four days later.
Third-place Manchester United is three points back from Chelsea but manager Alex Ferguson says fit-again Wayne Rooney could be among the team's substitutes for today's match against Wigan.