Poland's Iga Swiatek celebrates after winning her second round match against Danielle Collins of the U.S. REUTERS/Edgar Su[Source: Reuters]

World number one Iga Swiatek battled back from two breaks down in the final set to beat Danielle Collins 6-4 3-6 6-4 on Thursday and reach the third round of the
Australian Open for the fifth successive year.

Collins might be ranked 62nd in the world but has a good record at Melbourne Park and beat Swiatek in the semi-finals two years ago before going on to lose to Ash Barty in the title decider.

Four-times Grand Slam champion Swiatek has an excellent record against lower-ranked players but had to dig deep into her reserves to overcome Collins in a scrappy three-hour contest on Rod Laver Arena.

The 30-year-old Collins faltered in her serve at key moments in the match and Swiatek found her best tennis late in the decisive set to move onto a third-round clash with Czech Linda Noskova.