TORONTO (Reuters) – Karolina Pliskova began her reign as world number one with a ragged 6-3 6-3 second round win over Anastasia Pavlyuchenkova on a blockbuster Wednesday when eight of the top 10 ranked players were in action at the Rogers Cup.

Pliskova, playing in her first tournament since her shock second round defeat at Wimbledon, struggled with a misfiring first serve and was guilty of some lapses in concentration.

However, the lanky Czech was never seriously threatened as she disposed her 19th ranked Russian opponent in a tidy 70 minutes.

“I had a little bit (of nerves) before the match but during the match I felt much better especially at the end,” Pliskova said in a courtside interview.

“I think it was not the best tennis from my side but I was trying to improve in the match.

“I’m definitely happy I am through to the next round, the first match is always tough.”

Both sets followed a similar pattern, Pliskova surging to a 5-1 lead in the first and 3-0 in second. A loss of focus allowed Pavlyuchenkova to break and hold serve to trim the deficits.

But Pliskova snapped out of her brief funks each time and clinched her first win as number one with her seventh break.

A star-studded day on center court began with fourth-ranked Wimbledon champion Garbine Muguruza taming Belgian qualifier Kirsten Flipkens 7-5 6-2.

Second seed Simona Halep took care of surprise Wimbledon semi-finalist Magdalena Rybarikova with a relatively straightforward 6-3 6-4 win, while third seed German Angelique Kerber outlasted Donna Vekic 6-4 7-6(5).

American Venus Williams, playing in her first tournament since reaching the final at Wimbledon, again had to battle to advance as she defeated 21-year-old Katerina Siniakova 7-5 7-5.

Williams overpowered her Czech opponent with 12 aces and shrugged off several wasted break points after she converted just four of her 13 chances.

The 37-year-old will next face Elina Svitolina.

American teenager Catherine Bellis continued her brilliant form on the North American hardcourts by taking down eighth seeded Russian Svetlana Kuznetsova 6-4 7-5 to reach the third round.

The 18-year-old arrived in Toronto after reaching the semi-finals in Stanford last week.

Kuznetsova departed along with her 16th seeded compatriot Elena Vesnina, who suffered a 6-3 5-7 6-4 loss to Australian qualifier Ashleigh Barty, while Czech Lucie Safarova overcame 11th seeded Dominika Cibulkova 6-2 6-4.

In another upset, British seventh seed Johanna Konta was worn down by last week’s Citi Open champion Ekaterina Makarova 5-7 7-6(4) 6-3.

Tenth seed Agnieszka Radwanska cruised easily past Timea Babos 6-0 6-1, while Petra Kvitova was eliminated by Sloane Stephens 7-6(4) 3-6 6-2.