LONDON — Roger Federer is back at No. 1 in the ATP rankings, once again swapping spots with Rafael Nadal.
Federer’s title at the grass-court tournament in Stuttgart, Germany, last week pushed him up from No. 2 on Monday.
Nadal dropped down from No. 1 after sitting out last week following his 11th French Open championship earlier in the month.
This is the fifth time the top ranking has changed hands between Federer and Nadal. That’s the most switches at No. 1 in a single season since there were also five in 2003.
The record for most changes at No. 1 is 10, set in 1983, when John McEnroe, Jimmy Connors and Ivan Lendl all spent time there.
This is Federer’s record-extending 310th week at No. 1.
CHICAGO — Britain’s Kyle Edmund regained command in a tiebreaker and beat American Jack Sock on Friday as Team Europe took a 2-0 lead in the Laver Cup.
Edmund’s 6-4, 5-7, 10-6 victory followed Grigor Dimitrov’s 6-1, 6-4 win over Frances Tiafoe of Team World in the opener at the United Center.
Edmund broke Sock’s service to capture the first set 6-4. Sock, who came out to warm up wearing a Chicago Bulls jersey over his shirt, fought back and broke Edmund to go up 6-5 in the second set before serving it out as the crowd came alive.
Edmund then raced to a 7-2 lead in the 10-point tiebreaker that is used in the Laver Cup when the first two sets are split.
Sock was to play doubles later Friday with Kevin Anderson against the Team Europe star pairing of Roger Federer and Novak Djokovic.
Dimitrov had 13 winners and two service breaks to win the first set 6-1, finishing it off with one of his five opening-set aces.
Tiafoe was a late replacement for Juan Martin del Potro on Team World. The 20-year-old American played for in the Davis Cup semifinals last weekend in Croatia, losing the deciding match in five sets to Borna Coric.
He played much tougher in the second set Friday against Dimitrov, getting a service break for 4-4 before Dimitrov broke back and served out the victory in a match that featured extended baseline rallies.
ST. PETERSBURG, Russia — Top-seeded Dominic Thiem and fit-again Stan Wawrinka won their quarterfinal matches at the St. Petersburg Open on Friday.
Austrian player Thiem came through a tough encounter against Daniil Medvedev of Russia, firing 10 aces on his way to a 6-2, 3-6, 7-6 (2) victory.
His reward is a semifinal with Roberto Bautista Agut of Spain, who won 7-6 (0), 6-3 against Marco Cecchinato.
Experienced Swiss Wawrinka, aiming for his first title since sustaining a severe knee injury last year, next plays Martin Klizan of Slovakia after beating last year’s St. Petersburg champion Damir Dzumhur 6-3, 6-4.