Third seed Svetlana Kuznetsova brushed off the rust from a month-long layoff by dispatching Italy's Roberta Vinci 6-2, 7-6 to reach the third round of the Toronto Cup on Tuesday.
Seeing her first action since a quarter-final loss to Venus Williams at Wimbledon, the Russian had looked poised for a stress-free return to the courts but was forced to dig deep to put away a stubborn Vinci.
After blasting through the first set in 29 minutes, the 2004 U.S. Open champion needed an hour to prevail in a tense second set finally clinching the match in a tie-break 9-7.
Kuznetsova will next play the winner of American Meghann Shaughnessy and Czech Lucie Safarova for a place in the quarter-finals.
Also booking spots in the third round were Israeli 11th seed Shahar Peer with a 6-3, 6-2 win over doubles partner Tathiana Garbin of Italy and China's Shuai Peng, who advanced when 14th seed Katarina Srebotnik of Slovenia retired in the second set with a viral illness trailing 6-1, 4-2.
In opening-round action, Italian qualifier Maria Elena Camerin provided the first upset of the tournament, disposing of 15th seed Alona Bondarenko of the Ukraine 6-4, 6-3.
There were no such problems for Austria's Sybille Bammer, the 13th seed needing just 78 minutes to crush France's Emilie Loit 6-1, 6-2.
It was also a good day for the home crowd with three Canadians safely through to the second round for the first time 16 years.
Leading the Canuck charge was Stephanie Dubois with a shock 6-7, 6-4, 7-5 win over Japan's Ai Sugiyama.
Ranked 115th in the world, Dubois had looked ready to settle for a gritty but losing effort after Sugiyama roared back from 3-0 down in the third set to take a 5-3 lead.
But the 20-year-old Canadian stunned her 27th-ranked opponent, sweeping the next four games to collect what she said was one of the biggest victories of her young career.
"Even at 5-3, I told myself to be more aggressive and keep playing the way I was playing, I really believed that I could win," Dubois told reporters. "I keep playing my game but it worked out in the end."
Aleksandra Wozniak booked her spot when Russia's Anastasia Rodionova retired with a strained left quadricep down 6-4, 5-0 while Marie-Eve Pelletier and Ekaterina Shulaeva were playing in an all-Canadian nightcap.