Serena Williams books fourth-round spot at US Open

Serena Williams has secured her spot in round four of the US Open by beating Varvara Lepchenko in straight sets.

The top seed made light work of her opponent, taking the match 6-3 6-3 in a time of one hour and 37 minutes this evening.

Lepchenko lost serve on two occasions in the opener, allowing Williams to get an early foothold in the contest.

The second set went in an identical manner, with the world number 52 once more conceding breaks a couple of times to give her compatriot a comfortable victory.

Williams will face Estonia's Kaia Kanepi in the next round.