Clinging to a one-set, 4-3 lead, Maria Kirilenko had just taken treatment for a sore shoulder when she confronted the pain-in-the-neck play of Bethanie Mattek-Sands. The fast-charging American in the funky knee-high socks closed so tight to net she could have kicked it as she set up for a routine smash—a simple swing away from break point to level.

But even when your nose is at net and the entire court is open, nothing comes easy when you're playing an opponent capable of transforming hopeless defense into piercing defiance.

Guided by guess work, Kirilenko darted left, bounced high off the red clay, and stabbed an improvised high backhand pass down the line, sending a mortified Mattek-Sands racing in retreat, seeing her certain winner spit past in a cruel reversal of fortune. On the next point, Kirilenko correctly anticipated the direction of another smash, slamming another stunning backhand pass. Those improvised backhands were the daggers that sealed Kirilenko's 7-5, 6-4 victory, sending the 26-year-old Russian into her first French Open quarterfinal.

It was a tense two-setter featuring some gutsy attacking points, nervous misses, lost opportunities, timely strikes, momentum swings, illness, injury, and a confident close from Kirilenko, who was down 1-4 at the outset as Mattek-Sands came out streaking.

Driving her backhand down the line and continuously stepping inside the baseline, Mattek-Sands was up 3-0 after 15 minutes and held at love for 4-1. Kirilenko then began to settle in and play with more margin. She converted her third break point with a sweeping backhand swing volley winner to break back at 3-4. Mattek-Sands showed fine feel after, lifting a forehand drop shot to hold for 5-4; then she requested the tournament doctor and took treatment for nausea.

Matters took a stomach-churning turn for the 67th-ranked American when she double-faulted to gift a break point, and Kirilenko cracked a vicious cross-court fourhand to break for 6-5. Closure was complicated: Kirilenko could not find her first serve, double-faulted twice and was down 15-30, but Mattek-Sands couldn't make her play. When she sprayed a wild backhand wide, Kirilenko had won six of the last seven games to seize the 66-minute first set in which each woman won 43 points.

Three successive breaks opened the second set. After Mattek-Sands secured her first hold since the ninth game for 2-3, Kirilenko took a medical time-out for treatment of a sore right shoulder, receiving a deep muscle massage. In the longest game of the match, Mattek-Sands spun a forehand swing volley winner cross-court and raised her arms in mock celebration; she'd missed that shot a few times previously. A fine backhand volley winner brought the American to game point, where she drilled a forehand down the line, navigating a four-deuce game to hold for 3-4 and putting the pressure back on Kirilenko.

Those stirring backhand winners caused Kirilenko to unleash a celebratory scream and will probably haunt Mattek-Sands, who upset 2011 champion Li Na in the second round. Kirilenko closed the two hour, seven-minute win at love and will face two-time Australian Open champion Victoria Azarenka for a semifinal spot.