Manchester United midfielder Ryan Giggs says he will know when the time has come to retire from football.
The former Wales international turned 40 this week, and after 953 appearances for United it is unclear how much longer he can go on.
He played a starring role in the midweek 5-0 Champions League win at Bayer Leverkusen, illustrating his continued importance, and in an interview with the BBC he said he is concentrating on prolonging his career.
"There will be some incident, something will not be quite right, I'll feel different," Giggs said.
"I'm obviously wary of that because I'm still wanting to do well and wanting to focus on winning games."
Despite a slow start to the campaign that sees them in sixth in the league and seven points off pacesetters Arsenal, Giggs is confident they can retain their Premier League crown.
He said: "Of course we can win it again. We haven't got off to a great start but we've picked up more consistency lately.
"From the experience of the years, you know you just hang in there and hang in there and hopefully something will happen.
"When you're starting out you don't look forward 10 to 15 years, it's a million miles away.
"He [Sir Alex Ferguson] was a massive part of my career: you knew with the manager at the helm you always had a chance of success.
"From first meeting him at 12, 13 up until now; he still has an influence."
Giggs, who is now a first-team coach at United, also lauded the club’s decision to appoint David Moyes to replace Ferguson, claiming it was important to pick a British manager.
The Welshman said: "I'm enjoying it, the coaching role.
"It was always going to be a big ask whoever took over, he had such a successful time at Everton I think he deserves it.
"It's great for a British manager to have this chance because historically in the last 20 years these jobs have gone to foreigners.
"I'm enjoying playing under him and learning under him as a coach as well."