Novak Djokovic branded Andy Murray "an inspiration" as they prepare to resume old rivalries at the Madrid Masters.
Djokovic and Murray have played each other in multiple Grand Slam finals before the latter was struck down with a serious hip injury.
The journey back from that injury has been a long one for Murray, but he looked to be nearing something like his former self against Denis Shapovalov on Tuesday.
Djokovic is having fitness issues of his own following a highly disrupted 2022, although there was little evidence of that in his comfortable win over Gael Monfils.
The players will now face each other for the first time in five years on Thursday for a spot in the Madrid Master's quarter-finals.
Murray believes he should, in theory, 'have no chance,' while Djokovic is just happy to still have his former rival on the ATP Tour.
"He's moving well, playing better and better," Djokovic said of Murray. "It's really fantastic to see, because he's an important player for our game.
"He's made his mark in the history of our sport by winning multiple Slams and gold medals and [reaching] No. 1 of the world.
"He's one of the most important names that we have.
"To have him still compete is great, and to have him even play at [a] high level as the time goes by is impressive, considering the surgery and what he has been through in the past few years.
"His resilience and fighting spirit is really inspiring."