Serena Williams begins Wimbledon defense with victory

Serena on win: I never underestimate anyone (0:59)

Serena Williams reflects on her first-round win at Wimbledon and how special it is to be back at the All England Club. (0:59)

Serena Williams began her Wimbledon title defense with a comfortable but tentative win over Swiss qualifier Amra Sadikovic, winning 6-2, 6-4 on Centre Court. Williams won the final point on a line call challenge.

The six-time champion barely served any better than the 148th-ranked Sadikovic, who was making her main draw debut in a Grand Slam at the age of 27.

Williams' serve was shaky, she was broken once, and hit more unforced errors. But in her first match since her loss in the French Open final to Garbine Muguruza, Williams advanced to a second-round meeting with fellow American Christina McHale.