Roger Federer can prove he's back to his best and Andy Murray will test his recovery from surgery when they resume their rivalry in a hugely anticipated Australian Open quarter-final on Wednesday.
The Swiss master had been counted out of the Grand Slam reckoning after a disappointing campaign last year, when he bombed out of Wimbledon in the second round and lost in the US Open's last 16.
Federer won the latest of his record 17 Grand Slam tournaments at Wimbledon 2012 and has not reached a major final since, adding to perceptions he's lagging behind in an era dominated by Rafael Nadal and Novak Djokovic.
However, after turning back the clock with an impeccable last 16 performance against long-time sparring partner Jo-Wilfried Tsonga, the 32-year-old approaches the Murray match with renewed optimism. (Also read: Federer's revival faces a crucible)
He admitted both players had doubts hanging over them, with Murray only recently returned from back surgery and not totally convincing in Monday's four-set win over 'lucky loser' Stephane Robert.
"The draw is a very testing draw. I know it's tough. It's not easy for anybody right now at this stage of the tournament, because you don't want to have any hiccups right now," Federer said. (Also read: Can wife Mirka's pregnancy bring good luck to Federer?)
"I hope I can continue playing at a high level. What I've shown over the last three to four months to myself is that I'm more confident, that I know I'm most likely going to play okay in my next match."
The pair have not faced each other since Murray's five-set semi-final win at last year's Australian Open -- the only time the Scot has beaten Federer in four Grand Slam encounters.
Overall, the reigning Wimbledon champion leads Federer 11-9 and he has won three of their last four meetings in a sign that he is getting the better of the Swiss maestro.
Federer has turned to six-time Grand Slam champion Stefan Edberg, along with a new, bigger racquet, and says he's over the back problem and mental doubts which afflicted him last year.
"For me personally, I've overcome it. I don't have doubts any more. I know I'm going definitely in the right direction," he said.
"I feel like I can think ahead. I can think tactics. Everything else but my body, and that's very positive. I've overcome a lot in the last few months."
For Federer and Murray to win the year's opening Slam, Wednesday's victor will probably then have to beat Nadal in the semis and Djokovic in the final.
Nadal, the world number one, faces young Bulgarian Grigor Dimitrov, playing his first Grand Slam quarter-final, in Wednesday's other last-eight clash.
Murray said his expectations against Federer were relatively low, given he's in the first weeks of his comeback following the operation in September.
"It's a big match for me. Roger's played great tennis here in the past. It will be a very tough match for me," he said. (Also read: Angry Andy Murray is a 'smash hit' in Melbourne)
"I can't honestly say my expectations are as high as if I'd been playing for the last four months. It's been a good effort so far to get to the quarter-finals of a Slam this soon after back surgery.
"I've played him around 20 times. You know how you need to play against him, tactically things that work and things that don't work.
"Obviously last year's semi is pretty relevant because it's on the same court and it will be under the same conditions. But anything can happen."