Updates of day five of the ASB Classic with all four singles quarter-finals on the schedule.

Naomi Osaka becomes second semi-finalist

Fans and organisers will be breathing a sigh of relief after Naomi Osaka survived a scare to reach the semi-finals.

The seventh seed is the biggest remaining name in a tournament largely lacking star power and an upset loss in the quarter-finals would have been a blow for those with tickets to the weekend sessions.

Osaka ensured fans would get their money’s worth, though, coming from a set down to defeat Hailey Baptiste 6-7, 6-1, 6-2. The American put up a brave fight after progressing from a marathon match that stretched past 11pm last night, but in the end Osaka’s quality was too much to overcome.

The Japanese will now meet the winner of the semi-final between Americans Katie Volynets and Alycia Parks for a place in the final.

Osaka romps in second set

Naomi Osaka has wasted little time in levelling her quarter-final with Hailey Baptiste at a set apiece.

After falling 7-6 to begin the match, the seventh set waltzed to a 6-1 victory in the second set, setting up a decider with a semi-final spot on the line.

Osaka will be favoured to advance now against the world No 92 Baptiste, who was on court for almost three hours late last night.

Naomi Osaka drops first set

One of the biggest names remaining in the tournament will have to fight back from a set down to reach the semi-finals.

Naomi Osaka has dropped the first set in a tiebreak to American Hailey Baptiste, who had earlier served for the set before Osaka rallied back.

The Japanese seventh seed was unable to repeat that resurgence after falling behind in the tiebreak, with Baptiste showing few signs of wear despite her round-of-16 match finishing after 11pm last night.

Robin Montgomery reaches maiden semi-final

Excellent from the young left-hander. Finishes with an ace, her 12th of the match, and takes down Bernarda Pera 6-4, 6-4. The 20-year-old American will face either top seed Madison Keys or Clara Tauson for a spot in the final.

“I feel great. Just hope my team is happy with my serve,” she says after the victory.

Montgomery burns through a few break point chances but an early break is enough to take the opening set 6-4. She’s one set away from her first WTA semi-final.

It’s quarter-final day

Time to find out the top four of the tournament. Six of the eight quarter-finalists are American, with two of them featuring in the first match on Grandstand right now. There was a delayed start with some rain in Auckland this morning.

Bernarda Pera (USA) v Robin Montgomery (USA)

Followed by

7-Naomi Osaka (Japan) v Hailey Baptiste (USA)

1-Madison Keys (USA) v 5-Clara Tauson (Denmark)

8-Katie Volynets (USA) v Alycia Parks (USA)