Venus Williams
Venus Williams returns a shot from Lucie Safarova on day two of the Western and Southern Open.Reuters

Venus Williams left her winning streak in Canada as she was defeated by 16th seed Lucie Safarova in the first round of the Western and Southern Open on Tuesday.

The American had defeated sister Serena Williams to reach the Rogers Cup final earlier this month. However, Williams failed to maintain her Montreal momentum and lost 6-7 (2), 6-3, 6-4 to Safarova.

The seven-time Grand Slam champion took the first set in a tie-break but could not convert break points in the second set.

"I wish I could have felt today like I did in Montreal, just to make it more competitive," Williams said.

Safarova clinched her first win against the 34-year-old in five career encounters. Williams arrived from Montreal tournament on Sunday and opened on Tuesday, which left her with little time to practice and recover.

"It was definitely a quick turnaround, maybe would have been a little better to play a little later in the day," stressed Williams, who recently came into top 20 after Montreal runners-up finish.

Williams appreciated her counterpart's extraordinary performance.

"She just played so well. No matter what shot I hit she hit a winner, or if I hit it really deep she somehow managed to control it down the line," she pointed out.

The Czech led 5-2 in the third set and won a match point but Williams challenged and the call was overturned.

"That's a terrible feeling," Safarova said. "You think you've won and you have those emotions, and suddenly, you're back in the match against a great player. Then she broke me, and I thought, 'Uh, oh.' I've lost matches on challenges before. I told myself, 'I'm not losing this one."

Meanwhile, defending champion Victoria Azarenka withdrew from the tournament due to an injured right knee.

The Belarusian had a season full of injuries and was sidelined for several tournaments. She aggravated her right knee injury at the Rogers Cup, where she was defeated in the quarterfinals.

"I started to feel a little bit better and did everything I could, but it's just not enough time for me to feel good to play a full match," she said. "I'm going to get more treatment and get more work done and should be good for the U.S. Open."

Meanwhile, fifth-seeded Maria Sharapova defeated Madison Keys 6-1, 3-6, 6-3 in the first round.