LONDON, July 3 (Reuters) - Barbora Krejcikova continued her extraordinary transformation from doubles specialist to world-class singles player as she reached the last 16 at Wimbledon on Saturday. The Czech, who came from nowhere to win the French Open last month, outlasted Latvian Anastasija Sevastova 7-6(1) 3-6 7-5 in a two-and-a-half battle on Court Three. Including her title run on clay in Strasbourg before the French Open she has now won 15 successive singles matches and, for good measure, also won the French Open doubles. Amazingly, this is the 25-year-old"s first main-draw singles appearance at Wimbledon, although she already has a women"s doubles title at the All England Club from 2018 with partner Katerina Siniakova, with whom she also won the French. Before arriving at Wimbledon she had never played a Tour-level singles match on grass, having decided against any warm-up events, but she has looked totally at home on the surface. She was made to work hard by Sevastova though, with the Latvian twice serving for the opening set, and failing. Krejcikova dominated the tiebreak but Sevastova hit back to win the second set. The first 11 games of the decider all went with serve but Krejcikova found a glorious forehand return winner to get to within two points of victory before Sevastova dumped a backhand into the bottom of the net. Krejcikova could not take her first match point but converted the second when her opponent missed a backhand. She was joined in the last 16 by fellow Czech Karolina Muchova who beat Anastasia Pavlyuchenkova of Russia 7-5 6-3 to set up a clash with Spaniard Paula Badosa.