Roger Federer withdraws from Qatar Open with back injury . Federer sounded a cautious note ahead of the first grand slam of the season . ` five -time defending champion was due to play Jo-Wilfried Tsonga in the last four . Top seed Gael Monfils lost in straight sets to Qatar 's Gael Monfils in second semifinal . Roger Federer sweeps into semifinals of CNN .
Roger Federer withdraws from Qatar Open with back injury . five -time defending champion was due to play Jo-Wilfried Tsonga in the last four . Top seed Gael Monfils lost in straight sets to Qatar 's Gael Monfils in second semifinal . Roger Federer sweeps into semifinals of CNN .