Federer surpasses Lendl at Stuttgart Open

Roger Federer moved second on the list of ATP Open Era match victories by beating Florian Mayer in straights sets to reach the semi-finals of the Stuttgart Open.

The legendary Swiss moved level with Ivan Lendl by beating Taylor Fritz in the last eight and surpassed the Czech to take his tally of wins to an incredible 1,072 with a 7-6 (7-2) 7-6 (7-1) on Friday.

Only American great Jimmy Connors (1,256) has won more ATP matches in the Open Era than 17-time grand-slam champion Federer, who is just two victories away from claiming a title on his return from a back injury.

Top seed Federer, making his debut at the grass-court tournament, won an impressive 88 per cent of points on his first serve and thumped down 15 aces in a match with fine margins.

Federer dominated a first-set tie-break after Mayer had saved a set point when trailing 6-5 and the tournament favourite battled back from 2-0 down in the second before saving three set points and again coming out on top in a breaker.

The world number three, who has won all seven matches against Mayer, will now face Dominic Thiem after the rising star from Belgium fought back to see off Mikhail Youzhny 3-6 6-4 7-5.

Thiem, up to seventh in the rankings after his run to the semi-finals of the French Open, coughed up nine double faults but was able to advance despite his service struggles courtesy of three breaks to Youzhny's two.

Juan Martin Del Potro will face home hope Philipp Kohlschreiber in the other semi-final after the duo came through their last-eight matches.

Wildcard Del Potro battled back to get the better of fourth seed Gilles Simon 6-7 (3-7) 6-3 6-0, while Kohlschreiber was a 6-4 7-5 winner against Radek Stepanek.