The biting precision of Jelena Jankovic’s shots was as unwavering as the gleeful expression on the smiley-face vibration dampener embedded in her strings. The Serb absorbed Petra Kvitova’s power effectively, redirected drives down the line masterfully, and played with plenty of positive emotion in reeling off five consecutive games to seal a 6-1, 6-3 victory and roar into the Doha semifinals.

The former world No. 1 read Kvitova’s second serve as clearly as a text message. She often darted to her left while the Czech’s ball toss was in the air to intercept the slice serve on the ad side, and zapped deep returns that sometimes forced the 2011 Wimbledon winner to make demanding digs off the baseline. The left-hander’s first serve can be a lethal weapon, but Jankovic defused Kvitova's second delivery, winning 18 of 28 points played on the second serve. She broke six times—including all four of Kvitova’s service games in the opening set—book-ending the set with breaks.

Regripping her racquet after a 32-minute first-set fail, Kvitova tried to regroup without calling coach David Kotyza out on court. The third seed broke to open the second set, then earned her first hold to consolidate for 2-0.

Watching the ultra-talented but extremely erratic Kvitova can be like listening to a favorite radio station on the road: When Petra is dialed in she can flow like a string of stirring tunes, but when she loses the frequency, scattered shots and emotional static ensue. Holding a 3-1 lead, Kvitova was up 0-30 on Jankovic’s serve, but failed to put three returns into play after JJ slashed an ace for 15-30.

That escape act empowered Jankovic, who won 12 of the next 16 points. Jankovic is the more agile athlete who changes direction fluidly and closes quicker on the ball. Contrast that with Kvitova, who sometimes struggles to produce the right spin on her shots when she’s stretched. She was her own worst enemy in a four-error (including two double-fault) sixth game. She netted a forehand, then tapped her racquet against the court in disgust after dropping serve for 3-all. Jankovic then drilled a backhand return to set up a cross-court backhand that handcuffed Kvitova, giving the fifth seed another break and a 5-3 lead.

Kvitova managed to smack three winners to stave off three match points in the next game, and earned a pair of break points to get back on serve. The point of the match saw the pair square off in an exciting rapid-fire net exchange that ended with a Jankovic forehand pass. Jankovic closed it out on her fourth match point, as her forehand tight-roped across the top of the tape before dribbling over to end the 75-minute encounter.

A smiling Jankovic issued a "Ciao Mama" Valentine to her mother Snezana, but will return to work in doubles later today before facing ninth-ranked Angelique Kerber in Saturday's semifinals. Jankovic beat Kerber, 6-7 (8), 6-3, 6-1, in last month's Brisbane quarterfinals.