BEIJING, China - It was a bad day for past champions at the China Open - but another very good day for surging teenager Dayana Yastremska, who needed only 55 minutes to dismiss 2017 winner Caroline Garcia 6-1, 6-1.

Fresh off her maiden Premier quarterfinal showing in Wuhan, the 19-year-old Ukrainian blitzed winners left and right to score her second win in as many meetings against Garcia - a stark contrast to her first, a marathon victory in May's Strasbourg final that, at two hours and 58 minutes, is the longest WTA title match of the season to date. Today, though, Yastremska found the lines on the biggest points to take a series of tightly contested games in the first set - and then, from 0-1 down in the second, accelerated towards the finishing line at high speed, repeatedly swatting away the Frenchwoman's serve with no-holds-barred returning to rattle through 24 of the last 31 points of the match.

Simona Halep posted an emphatic straight-sets win over Rebecca Peterson (Jimmie48/WTA)

Also in a stingy mood was No.6 seed Simona Halep, who showed no sign of the lower back injury that had forced her to retire in the third round of Wuhan last week while trailing Elena Rybakina. The Wimbledon champion proved nigh-impossible for qualifier Rebecca Peterson to hit through as she raced to a 6-1, 6-1 victory in one hour and 11 minutes.

Saving all five break points against her while capturing Nanchang champion Peterson's serve three times in the first set and twice in the second, Halep was relentless in her refusal to relinquish control, encapsulated by a marathon 10-minute, seven-deuce hold for 4-1 in the second set that saw Peterson throw everything she had at the Romanian to no avail.

Elsewhere, World No.104 Christina McHale came out on top of a seesaw win over wildcard and two-time champion Svetlana Kuznetsova 6-0, 1-6, 6-3 in one hour and 50 minutes - the American's second Premier main draw upset as a qualifier in as many weeks following her defeat of Anastasija Sevastova in Wuhan. The eliminations of Kuznetsova and Garcia mean that three of the four former Beijing winners in this year's main draw have exited in the first round, with only defending champion Caroline Wozniacki remaining.

But as the past champions fell, 2011 runner-up Andrea Petkovic survived. Prague and Palermo champion Jil Teichmann served for the opening set of their clash - but qualifier Petkovic would save one set point before edging away for a 7-6(4), 6-3 win.

Meanwhile, Yulia Putintseva put the ankle injury sustained in the closing stages of her Osaka quarterfinal loss to Naomi Osaka, which forced her to retire against Kuznetsova in the first round of Wuhan last week, to speed past qualifier Anna Blinkova 6-0, 6-1 in one hour and nine minutes; while Acapulco champion Wang Yafan asserted her authority in the Chinese pecking order to defeat 18-year-old compatriot and wildcard Wang Xinyu 6-1, 6-2 in only 52 minutes

Wang Yafan came out on top of an all-Chinese derby against teenage wildcard Wang Xinyu (Getty)