In his first match in a month, Roger Federer overcame a stiff challenge from American teenager Taylor Fritz to reach the Mercedes Cup quarterfinals with a 6-4, 5-7, 6-4 win Thursday. The match began the day before but was halted by rain with the top-seeded Federer leading 4-3 with a break of serve. A return into the net by Fritz gave Federer the first set. Federer saved two set points before a forehand winner by Fritz and a forehand error by Federer gave the middle set to the 18-year-old American. Federer struggled to hold serve early in the third but broke for 5-4 and clinched the match with a backhand winner. "It was very difficult, just as I knew before the match," Federer said. "I was more fortunate at the end." A back injury forced the 34-year-old Federer to skip the French Open, the first time he missed a Grand Slam after 65 straight appearances. "After such a long injury, you need to find your rhythm," Federer said. It was Federer's 1,071st career win on the tour, tying him with Ivan Lendl. Only Jimmy Connors has more, with 1,256. For Fritz, it was only his fourth tour match on grass. The Stuttgart tournament is on grass as a tuneup for Wimbledon, which Federer has won seven times. Now ranked No. 3 in the world, Federer is next up against Florian Mayer. While Federer may have been rusty, second-seeded Marin Cilic was completely off, losing to the veteran qualifier Radek Stepanek 7-6 (4), 7-5. Stepanek won despite firing fewer aces, 10 to 12, and serving more double-faults, 6-1. Third-seeded Dominic Thiem, who beat Federer in the third round of the Italian Open before Federer took the injury break, edged Sam Groth 7-6 (3), 7-6 (2), and No. 4 Gilles Simon beat Jan-Lennard Struff 6-4, 4-6, 6-2. Thiem, a semifinalist at the French Open, next plays Mikhail Youzhny, who beat Sergiy Stakhovsky 6-3, 7-6 (1). Stepanek plays Philipp Kohlschreiber. Wild card Juan Martin del Porto, coming back from a wrist injury, beat John Millman 6-4, 6-4. He will next play Simon. Federer, meanwhile, had no sympathy for Maria Sharapova, saying Thursday he backs a "zero tolerance" stance against doping. Russian star Sharapova was handed a two-year doping ban Wednesday after testing positive for the banned medication meldonium at January's Australian Open. "I only heard the headlines, I didn't quite get into all the details but to me it's about zero tolerance," said Federer. "It doesn't matter if they did it on purpose or not — I don't really see the difference. You need to know what goes into your body, you have to be 100% sure of what's going on, if you're not, you're going to be damned. "Of course she's got the right to fight the case, like everybody else as well. I'm just for zero tolerance. "I stay by my word that we should be saving blood samples for 10, 15, 20 years to come, so you have to scare away the people who think they could cheat." Zheng upsets Konta In Nottingham, China's Zheng Saisai put a dampener on British favorite Johanna Konta's joy at breaking into the world's top 20 by beating her 6-4, 7-5 in the second round of the WTA Nottingham tournament Thursday. Zheng will face either eighth-seeded Christina McHale or Konta's compatriot Tara Moore. Australian Ashleigh Barty joined Zheng in the last eight with a hard fought 6-0, 4-6, 6-4 win over Andrea Hlavackova. For Barty it will be her first WTA quarterfinal since 2014 after she took time out to play cricket. Kozlov upsets Johnson Wild card Stefan Kozlov upset fourth-seeded Steve Johnson 6-3, 6-4 to reach the quarterfinals of the Ricoh Open Wednesday. Second-seeded Bernard Tomic had a routine 6-4, 6-3 win over Aljaz Bedene, fifth-seeded Sam Quarry fired 11 aces and never faced a break point in beating Tatsuma Ito 6-3, 6-4 and eighth-seeded Nicolas Mahut also made the last eight by defeating Paul-Henri Mathieu 4-6, 6-1, 6-4. On the women's side on the Rosmalen grass courts, third-seeded Kristina Mladenovic rallied to beat qualifier Natalia Vikhlyantseva 5-7, 6-3, 6-4. Sixth-seeded CoCo Vandeweghe beat Nao Hibino 6-2, 6-3 and Madison Brengle outlasted Richel Hogenkamp 7-5, 5-7, 7-5.
