Six-times champion Roger Federer has overcome back spasms to reach his 33rd successive grand slam quarter-final with a four-set win over Xavier Malisse.

Federer required a medical timeout to have painkillers midway through the first set before settling down to beat Malisse 7-6 (7-1) 6-1 4-6 6-3 in two hours and and 11 minutes.

The 16-times major winner next plays either Russian Mikhail Youzhny or Uzbek Denis Istomin on Wednesday for a likely semi-final showdown with world No.1 and defending champion Novak Djokovic.

Turning 31 next month, Federer can displace Djokovic as world No.1 if he matches Pete Sampras’s record seven titles at the All England Club.

Such a dream scenario would also draw the Swiss superstar level with Sampras for the longest total reign as world No.1 – 286 weeks.