Dechy won the first five points of the tiebreaker before connecting on a forehand volley at match point to clinch her third win in five career matches against Srebotnik.
Third-seeded Maria Kirilenko avoided an upset with a 1-6, 6-2, 7-5 win over Canadian qualifier Stephanie Dubois 1-6, 6-2, 7-5 in their second-round match.
Second-seeded Nadia Petrova, the highest seed remaining after No. 1 Marion Bartoli retired on Tuesday with abdominal pain, also advanced by easily beating Julie Ditty of the United States 6-1, 6-1.
Kirilenko came from behind twice, after losing the first set and seeing her serve broken at the beginning of the third.
"I knew it was going to be a tough match,'' said Kirilenko, who lost a third-set tiebreaker to the Canadian at Montreal last week.
Dubois broke the Russian in the first game of the third set and then hit the baseline with a lob to hold serve for 2-0. Kirilenko pulled even with a service break in the sixth game, and both players held serve until the last game when Dubois sent a backhand long on Kirilenko's third match point.
"I made a lot of mistakes in the first set,'' said Kirilenko. "When the second set began, I decided I had to change up. I started hitting a lot of heavy balls and lobs, and I saw she didn't know what to do with those. Sometimes you have to win ugly.''
Kirilenko will play Sabine Lisicki of Germany, who beat Camille Pin of France 6-3, 6-4. Lisicki used a 7-0 advantage in aces to help overcome nine double faults.
Petrova, a Wimbledon quarterfinalist, won 11 consecutive games after Ditty held serve to open the match. Ditty double-faulted on chances to hold serve in the third and fifth games, allowing the Russian to take control. After that, Petrova's main challenge was staying focused in the second-shortest match of the tournament - just over 57 minutes.
"After I broke her to go up 2-1 and 4-1, she seemed to lose her confidence,'' said Petrova, who questioned a line call on a serve by Ditty while leading 5-0 in the second set. "I knew I still had to be at the top of my game and not give her any easy games. What I liked about today was I was able to keep the pressure on - to ensure my level of play and not give her any easy points.''
Petrova will play American wild card Lilia Osterloh, who reached the quarterfinals of the Western and Southern Financial Group Women's Open for the second consecutive year, this time with an easy 6-4, 6-1 upset of Petra Cetkovska of the Czech Republic.
"I pressured her forehand a little bit,'' said Osterloh, who grew up in Columbus, about an hour north of the tournament site. "Once I got my serve going and my feet moving, I was able to move the ball around on her and make her play.''
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