NEW YORK – When Roger Federer smacked a backhand return winner off his opponent’s 142 mph (229 kph) serve Friday night, he glanced at the speed readout, just to find out exactly how difficult what he’d done had been.
Then, later in his 6-4, 6-4, 6-4 victory over big-hitting Sam Groth in the U.S. Open’s second round, Federer again checked out the digital display in Arthur Ashe Stadium after getting a 147 mph (237 kph) offering over the net en route to taking that point, too.
The 17-time major champion said that while he couldn’t know for sure what the precise speeds were, he’s usually pretty good at guessing.
“I’m aware of every serve, how hard it is after the point when he goes big, because I think it’s interesting and I want to see,” Federer said. “Sometimes I feel it, as well. I’m like, ‘That felt like 138,’ and it might be just a couple off. It’s the same with my own serve. I can judge it probably (within) a few miles an hour.”
A reporter jokingly asked Federer whether his eyes were open when he got his backhand on the fastest serve of the match.
“Got to check the replay. I’m not sure. It was maybe one of those moments,” Federer said with a laugh as he shut his eyes and pantomimed stretching out his right arm in hopes of making contact with the ball.
In the third round, Federer — who has won five titles at the U.S. Open — will face 42nd-ranked Marcel Granollers of Spain.
The second-seeded Federer improved to 54-1 in second-round Grand Slam matches; the only loss came at Wimbledon last year. He’s also now 24-1 over his career in matches under the lights in Arthur Ashe Stadium.
“I was trying not to get caught up in the whole ‘Roger act’ out there. You walk out, you get a few cheers. He walks out and the crowd goes ballistic,” Australia’s Groth said. “So from the word ‘Go,’ you know he’s there.”
Doing an impressive job of handling the 104th-ranked Groth’s powerful serves, Federer limited him to eight aces and broke him five times.
In the women’s draw, Italy’s Sara Errani got a little motivation before her match against Venus Williams after coming across a video posted on Twitter. It showed a pair of former players and coaches, Brad Gilbert and Darren Cahill, forecasting Friday at Flushing Meadows. Both picked Williams to win.
The 13th-seeded Errani’s ears perked up particularly when Gilbert referred to her “cottage cheese” serve and predicted she’d win only four games.
What she did was win a riveting third-round match of wild momentum swings. The 19th-seeded Williams, a two-time U.S. Open champion, came within two points of victory four times before succumbing to Errani 6-0, 0-6, 7-6 (7-5).
As if needing a reminder of what she’d seen online, Errani was interviewed for TV by Cahill before the match, and by Gilbert afterward.
“Let’s just say that during the match I thought about that (video) more than once,” said Errani.
Williams is 34, dealing with an autoimmune disease, and hasn’t been to the fourth round at a major since 2011.
She also played a doubles match Thursday with her sister Serena that lasted about 2 ½ hours and finished shortly before 8 p.m.
“I guess the schedule definitely wasn’t ideal,” Williams said. “It was just such a late match.”
Errani’s next opponent will be another surprise winner: 32-year-old qualifier Mirjana Lucic-Baroni of Croatia, who eliminated No. 2-seeded Simona Halep of Romania 7-6 (8-6), 6-2.
“I feel,” she said, “like a little kid; like this is the first time ever.”
Half of the top eight seeded women already are out, with Halep joining No. 6 Angelique Kerber (beaten 6-1, 7-5 Friday by 17-year-old Belinda Bencic of Switzerland), and earlier losers No. 4 Agnieszka Radwanska and No. 8 Ana Ivanovic.
No. 5 Maria Sharapova, a five-time major champion, avoided that sort of upset by beating 2013 Wimbledon runner-up Sabine Lisicki 6-2, 6-4.
Sharapova trailed 3-1 in the second set, but took five of the last six games after Lisicki was told by chair umpire Carlos Ramos that he thought she was receiving coaching help, which isn’t allowed during Grand Slam matches.