Six-time champion Roger Federer landed in a record 33rd straight Grand Slam quarterfinal with a less-than-routine four-set victory at The Championships, Wimbledon.

The third-seeded former world No. 1 great held off capable Belgian grass- courter Xavier Malisse 7-6 (7-1), 6-1, 4-6, 6-3 on the famed Centre Court at the All England Lawn Tennis Club. The victory also marked the 850th of Federer's remarkable career.

Federer and Malisse had to wait out a brief rain delay on Day 7 and the Swiss icon had to summon a trainer to treat an achy back while leading 4-3 in the opening set.

The 30-year-old Federer ultimately prevailed in 2 hours, 11 minutes with the help of six breaks and nine aces. Malisse also recorded nine aces, but managed only half as many breaks as his Swiss counterpart on a dreary Monday.

Malisse beat Federer in their first ATP meeting in 1999, but the sublime Swiss has now won their last 10 matchups, including a pair of battles at Wimbledon.

Federer was asked right after the match if his back was okay.

"I wouldn't be doing this interview right now if it wasn't," he said.

The 31-year-old Malisse was a Wimbledon semifinalist 10 years ago.

In addition to his six titles, Federer was the 2008 Wimbledon runner-up to Rafael Nadal, as the two men played in an epic five-set final that year regarded as the greatest match in tennis history.

Federer, who reached seven straight Wimbledon finals from 2003-09, is still seeking his first Grand Slam title since the 2010 Australian Open.

The Swiss star will meet 26th-seeded Russian veteran Mikhail Youzhny in the round of eight.

Youzhny had been 0-6 in his previous fourth-round matches at the AELTC, but the gritty Russian finally secured a berth in his first-ever Wimbledon quarterfinal by outlasting Uzbekistan's Denis Istomin 6-3, 5-7, 6-4, 6-7 (5-7), 7-5.

The 30-year-old Youzhny has now reached at least the quarters at all four majors, including trips into a pair of U.S. Open semifinals.