Three-times French Open champion Gustavo Kuerten knows what it is like to have a career plagued by injury but believes Rafael Nadal will come back strong from his latest ailments.
Spaniard Nadal has not played since a shock defeat by Nick Kyrgios at Wimbledon, since when a wrist problem and a troublesome appendix have sidelined the former world number one.
Nadal, whose ninth French Open title in June was a rare highlight in a difficult year, will return to action after Christmas and Kuerten expects the 28-year-old to be challenging for more grand slams in 2015.
"It's worrying for all of us who love watching him when he's injured but then he keeps surprising us," the 38-year-old Kuerten, forced to retire in his prime due to hip problems, told Reuters.
"He turned it around last year and finished up as the number one again. Anything is possible for Rafa, but it depends on his physical condition and the level of Novak (Djokovic)."
Kuerten does, however, urge caution.
"His style has a massive impact on the body, it's based on his physical performance a lot," said Kuerten, affectionately known around the world as "Guga".