Belinda Bencic needed three sets to see off American Varvara Lepchenko at the Ricoh Open in ‘S-Hertogenbosch, Holland.
The #1 seed, who had been absent with a back injury for the past two months, appeared to be lacking match fitness initially but came through the test 3-6 6-3 6-2.
And her big weapon of her thumping serve deserted the 19-year-old throughout the 106-minute encounter, sending down six double faults.
And Lepchenko pounced on her Swiss opponent’s struggles to break serve in the fourth game and wrapped up the opening set 6-3 after 35 minutes in their first ever meeting.
But battling Bencic, the youngest player in the world’s top 10 tuned up her game and lost her rustiness to send down piledrivers that left 30-year-old Lepchenko bewildered.
The current Eastbourne champion went on the attack, winning her serve with ease and easily breaking in the next game for a 2-0 advantage.
Only to stutter once more and allow the veteran to square matters with a break of service. The Swiss teen sensation looked to be on the ropes, but she held her nerve to win the fifth game and edge ahead.
Lepchenko’s serve in the sixth game, the longest of the contest, was fiercely contested with the American thundering a winner to level.
Bencic turned on the style and overpowered her opponent to capture the set after 37 tense minutes.
She maintained her momentum on the deciding set, Lepchenko running out of steam as well as ideas, to soar into a 3-1 lead.
Yet a wasted opportunity for a 4-1 advantage permitted Lepchenko to trail 3-2 and give the teenager a real scare.
The top seed went all out for the kill, breaking the veteran and then holding her service game to take control of the encounter with a 5-2 lead.
Serving for the match was no simple task for Bencic against the aggression of the American, but she triumphed on the third match point when Lepchenko sent the ball wide of the target.
Bencic explained: “My level is still not there where I want it to be, so I don’t think it was a really good match from my side.
“All I could do myself was just to fight and keep going. That’s what I’m trying every day so I’m just hoping to improve.”
The success sets up an all-Swiss quarter-final at the Ricoh Open, Bencic will face qualifier and Fed Cup team-mate Viktorija Golubic.
Bencic added: “I’m very happy for her that she’s having such good results, and it’s very positive for the Swiss to have two players in the quarters.
“I’m really good friends with her, so I hope that it will be a good match. I will have fun out there and try to fight like today.”
Bencic’s breakthrough season was kick-started on grass last term, finishing runner-up here at the Ricoh Open, becoming a shock winner at Eastbourne’s Aegon International and then reaching the last 16 at Wimbledon.