Roger Federer has admitted that he was worried over his safety during Wednesday's victory over Lu Yen-Hsun at the Shanghai Masters.

The Swiss world number two was recently the subject of a death threat by a Chinese blogger ahead of the tournament.

"I felt fine. There was maybe one quick thought. I saw one of the bodyguards outside of the court. I thought, still around, obviously. I have bodyguards every time I play a match on a centre court, which is normal.

"Once the match started, got underway, I never thought about it again."

Federer went on to defeat the world number 64 6-3 7-5 to set up a quarter-final encounter with fellow countryman Stanislas Wawrinka.