London:There were no major upsets on day six of the Wimbledon and both the defending champions Roger Federer and Maria Sharapova pulled safely through to the last 16. Federer survived a scare before sealing his place in the last 16 with a 6-2, 6-7, 6-1, 7-5 victory against Nicolas Kiefer of Germany. The Swiss has now won 32 matches in a row on grass, closing in on Bjorn Borg's record of 41. But the main thing is that he is still on track for a hat-trick of triumphs at the All-England Club. In the women's draw, Maria Sharapova is into the second week of the championships following her 6-2, 6-4 third round victory over Katarina Srebotnik. The defending champion wrapped up the Slovenian challenge in an hour and a half. Kim Clijsters will face top seed Lindsay Davenport of the United States in the last 16, thanks to her comfortable win over Italian Roberta Vinci, 6-3, 6-4. Clijsters had only surrendered a total of seven games in her opening two rounds at the 2005 Championships. French Open finalist Mary Pierce brushed aside the 17-year-old Serbian Ana Ivanovic on Saturday to win a place in the last 16. In marked contrast to her struggle in the previous round, Pierce saw off the six-foot Wimbledon debutant with an easy win in straight sets. Venus Williams, champion in 2000 and 2001, moved into the fourth round to set up a possible clash with her sister Serena. She defeated Daniela Hantuchova 7-5, 6-3. It was the American's seventh straight victory over the Slovak.