World No. 1 Serena Williams admits that she played too cautiously at times and was a little tight in her fourth-round upset at the hands of Sabine Lisicki at Wimbledon. Lisicki snapped Serena's career-best 34-match winning streak with a 6-2, 1-6, 6-4 victory.

"I just definitely feel like I could have went for it a little more on some of the shots,” Williams said. “Definitely should have made some shots. I think Sabine played really well, as well. She always plays really well at Wimbledon, so I knew going in it would be a tough match. I definitely had my opportunities and I didn't take them. I definitely feel like I would try at some points, then maybe I backed off a little bit at some points.

"Going forward, if I want to be successful, if I plan on being successful, I'm never going to do it backing off.  I have to play the game I can play. For me that's being more aggressive.”

The 16-time Grand Slam champion's next scheduled tournament is the clay-court event in Bastad, Sweden the week after Wimbledon. She is not scheduled to play in North America until the Rogers Cup, which beings on August 5 in Toronto.

Even though her loss to Lisicki was her first since February and she won five titles in between Doha and Wimbledon (including her 16th Grand Slam title at Roland Garros), Williams said it was tough to see the positive in defeat.

“I probably couldn't be more disappointed,” she said.