Roger Federer of Switzerland (L) holds his winners trophy and Andy Murray of Britain holds his runners-up trophy after Federer defeated Murray in their men's singles final tennis match at the Wimbledon Tennis Championships in London July 8, 2012
Federer qualified for the quarter-finals with a 7-6 6-4 win over the German Mischa Zverev.
Addressing Murray's drop-off in form having achieved number one status at the end of 2016, Federer said: "Andy was tired after getting to No1 at the end of last year and then has been struggling with injuries.”
Murray crashed out at Queen's against 90th-ranked Jordan Thompson as he was readying himself for Wimbledon, and also failed to defeat Stan Wawrinka in the semi-finals of this year's French Open.
Murray, Wawrinka, Federer Rafael Nadal and Novak Djokovic are not the forces they once were in men's tennis, and 35-year-old Federer is now considered the favourite for Wimbledon by punters.
“I think the second part of the season will be really crucial for Andy, and Novak [Djokovic] as well," he added. "I think the second half of the season is going to be really, really interesting.”
Should Federer win at Halle, he will enter Wimbledon as the third seed.