Serena Williams battles to win over Timea Bacsinszku

Serena Williams has booked a place in the semi-finals of the BNP Paribas Open with a 7-5 6-3 victory over 27th seed Timea Bacsinszky at Indian Wells.

Despite holding off a strong challenge to secure the victory, it was far from easy for the world number one as she battled with difficulties on serve for much of the match.

It was a disappointing start for Williams as she lost her serve in the opening game, and Bacsinszky looked confident in longer rallies until allowing the American to break back midway through the opener.

Williams survived two break points in the 11th game before making the breakthrough moments later to take a vital lead over her Swiss opponent.

Bacsinszky was soon struggling with her own serve as the two players traded breaks in the opening four games of the second set.

The turning point came when Williams converted again in the eighth game, and an inconsistent performance was completed when the top seed capitalised on match point at the second attempt to set up a semi-final clash with Simona Halep.