London - World number one Serena Williams lost her cool but not the match in a 6-7 (9), 6-2, 6-4 win over Christina McHale in the second round at Wimbledon.The defending champion needed two hours and 29 minutes to down her compatriot on Centre Court, and will face a fine in excess of £5 000 for repeatedly smashing her racquet.Williams first took out her frustrations on her racquet after losing the first set tiebreaker, and later flung it onto the turf as she went 0-2 down in the second set.However, the 34-year-old recovered to down McHale and set up a third-round meeting with Annika Beck."I was just really, really, really angry. I had a lot of chances," Williams, who hit 40 unforced errors, said after the match."She got really lucky on some shots. She just was playing great. I was a little disappointed in myself at that point."The top seed is joined in the third round by her older sister, Venus, who beat teenager Daria Kasatkina 7-5, 4-6, 10-8 in a match that was interrupted by rain on three occasions. Williams will face 12th seed Carla Suarez Navarro in the third round after the Spaniard defeated Marina Erakovic 6-2, 6-2.