Wimbledon 2012 - After Reaching Top 100, Unlikely American Advances to Round of 16 WIMBLEDON, England - A year ago, Brian Baker was unranked in men's tennis. He was preparing to drive nine hours to Pittsburgh, to play in his first professional event in four years. He was serving as an assistant coach at Belmont University in Nashville. He was participating in something called the Middle Tennessee Tennis League. Leon Neal/Agence France-Presse - Getty Images Brian Baker, who was ranked No. 456 in January, defeated Benoît Paire of France in four sets. Anja Niedringhaus/Associated Press Serena Williams was extended to three sets (9-7 in the third) before ousting Zheng Jie of China on Saturday in the third round at Wimbledon. Sara Errani of Italy failed to win a single point in the first set against Yaroslava Shvedova of Kazakhstan and was eliminated. On Saturday, he advanced to the fourth round of Wimbledon. He is one of 16 men remaining, a group that includes Roger Federer and Novak Djokovic, but not Rafael Nadal. To make his comeback story even more remarkable, even more improbable, Baker surmounted windy conditions and the Frenchman Benoît Paire, who lost nine straight games, a racket and his composure. Asked when he realized that he could play at the level required to reach the second week of a Grand Slam tournament, Baker smiled and said, "Right now." In truth, it began far earlier, as he excelled as a top junior, as he recovered from five operations, as he won that tournament in Pittsburgh, and another in Georgia, and reached a final last month in Nice, France. On the clay there, he lost to Nicolás Almagro, but no matter: his confidence had soared. He felt validated. With his 6-4, 4-6, 6-1, 6-3 victory, Baker moves on to face Philipp Kohlschreiber of Germany, who halted Nadal's conqueror, Lukas Rosol, in three sets. Asked what he knew about Baker, Kohlschreiber was honest. "Nothing," he said. Baker's ranking, nonexistent last June and No. 456 in January, has climbed to around No. For reaching the top 100, Baker, who earned a berth here through qualifying, will gain direct entry into the United States Open. "I'm sure I will," Baker said when asked if he's still having any pinch-me moments. It's been unreal. Just as unreal was the first set won by Yaroslava Shvedova of Kazakhstan, who did not lose a point against Sara Errani of Italy. Shvedova won 24 straight points, then held on to oust Errani, the French Open runner-up, 6-0, 6-4. On Centre Court, Serena Williams and Zheng Jie of China engaged in a taut three-setter that tested the boundaries of Williams's persistence and Zheng's consistency from the baseline. Williams prevailed, 6-7 (5), 6-2, 9-7, but only after Zheng staved off two match points. Williams has won all six meetings against Zheng, including an intense Wimbledon semifinal in 2008, but the last three all went three sets. That is all Baker needed in winning his first two matches here, but Paire tested him, mixing gallant shot-making with a volatile personality. Before putting away a forehand volley to end the match, Baker muffed a forehand sitter on his first match point, which, he said, "I probably wouldn't miss if it was the quarters of a Challenger and not trying to get to the round of 16 at Wimbledon." But here he is anyway, as unlikely as it once seemed. "This is awesome," Baker said.