LONDON, July 7 : Coco Gauff fought back from a set down to reach the Wimbledon semi-finals for the first time after beating friend and former doubles partner Jessica Pegula 4-6 6-3 6-3 in an all-American Centre Court clash on Tuesday.The seventh seed and two-time Grand Slam winner, now the highest ranked player left in the women's singles draw, was on the back foot from the start against a fourth-seeded opponent who broke her in the opening game.Gauff got things under control in the second set, although she still had to survive two break points in the opening game, and halved the number of unforced errors as she fought back to break Pegula for 5-3 and hold serve.The former U.S. and French Open winner led the match for the first time when she broke Pegula to go 2-1 up in the final set. Her