Andy Murray has done exceedingly well to make it into the quarterfinals of the 2014 Australian Open after a swift return to action following back surgery last fall.
Up next is Roger Federer, who enters the quarterfinals match on a hot streak and represents someone who will oust the British star quickly if Murray doesn't show up with his A-game.
Federer complimented his rival after both advanced past Round 4, while offering a subtle challenge, as noted by ESPN.co.uk:
"Andy's done great to reach the quarter-finals so soon after surgery and let's hope his fitness holds out because we always have great matches and I'm really looking forward to it."
If anyone knows how difficult it is to come back and play at a high level after surgery, it's Federer, who also knows Murray might not be able to handle a five-set match in the roiling heat in Melbourne.
As a tuneup to the Australian Open, Murray competed in the Qatar ExxonMobil Open, but he was knocked out in his second match by Germany's Florian Mayer in three sets (two sets to win).
He hasn't exactly been on top of his game in this tournament, either, needing four sets to get past Stephane Robert (No. 119) in the fourth round and dealing with a couple of hiccups in previous rounds.
A bit of rust is to be expected from Murray as he works himself into top form, but he won't survive this upcoming match with a similar effort.
On the other side, Federer hasn't dropped a set yet at the Australian Open, and the ease with which he dispatched Jo-Wilfried Tsonga in Round 4 showed he's gaining momentum heading into the final rounds, rather than losing steam.
Greg Garber of ESPN.com elaborates:
Wielding a new, slightly larger racket, serve-and-volleying with abandon, on Monday night Federer aggressively attacked the net more than we are accustomed to seeing. Federer won 34 of his 41 net points, a tidy 83 percent. Maybe it's because he's healthier than he has been in recent years -- and confident, too.
Federer's 2013 campaign showed he's not ever going to be as dominant as he was in his heyday. However, the legendary champion is still quite capable of putting forth excellent efforts in big tournaments.
Who you got?
If Murray shows up with any weakness in his game, or if his back starts acting up in the slightest, then Federer will exploit him with a relentless attack.
Murray cannot afford another lapse like we saw in his match against Robert, who wasn't able to capitalize on the opening left by the Wimbledon champ in the third set. If he gives Federer an inch, he'll lose by a mile.
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