Maria Sharapova was introduced as the new global ambassador for Porsche at the start of the week. But the top-seeded Sharapova looked like a lost tourist stranded by the roadside as Angelique Kerber won eight of nine games to surge ahead 2-0 in the decisive set of today’s Stuttgart semifinals.

Undaunted, Sharapova found an extra gear, pressed the power pedal to punish the German’s short offerings and roared back for a 6-3, 2-6, 7-5 victory to reach her second straight Stuttgart final.

It was the 15th consecutive clay-court victory for Sharapova, who has shown her trademark resilience  in scoring three consecutive three-set victories.

The reigning Roland Garros champion appeared to be in command as she cruised through the first set, but the left-handed Kerber began to drive her shots into the corners and surprise Sharapova with her forehand down the line. A curling crosscourt forehand from Kerber drew a wild backhand error as she broke for a 4-1 second-set lead. Kerber cracked her fourth ace and used a service winner to hold for 5-1.

Typically, Sharapova’s two-handed backhand is such a rock-solid shot you can imagine her rolling out of body and slamming the two-hander into the corner while still half asleep. But she lost the range on that shot in the second set, sometimes striking it too flat and finding net, while lofting it long on other occasions. A Sharapova backhand return missed the mark deep and Kerber collected the second set, 6-2, despite serving just 48 percent. Sharapova littered 14 errors in the set, compared to eight for Kerber, who scraped more balls back into play and absorbed some of Sharapova’s deep blasts, by bending low and using her legs to help lift back replies.

Sharapova used the bathroom break to reset after dropping the second set to Ana Ivanovic in Friday’s quarterfinals and took another bathroom break to regroup today. But she dumped successive double faults to hand Kerber the break in the opening game of the third set and the German backed it up at love for a 2-0 lead. Sharapova’s short-term memory loss on court has long been a strength: She can erase a series of errors from her mind and strike back with aggression. After a slide that saw her lose eight of nine games, Sharapova did just that, ripping the ball down the line off both wings to reel off three straight games for a 3-2 lead. Kerber showed stiff resolve in fighting off three break points to withstand the longest game of the match, an 11-minute struggle, and level at 3-all.

Sharapova navigated a challenging deuce game, holding for 4-3 on the strength of a service winner and a stinging forehand winner crosscourt. Empowered, Sharapova smacked a forehand return winner down the line before punishing a forehand crosscourt breaking for 5-3. Kerber wasn’t through yet: She broke at love and held at 30 for 5-all, but that would be her last stand. Hitting with greater authority and accuracy, Sharapova reeled off eight straight points to seal the two hour, seven-minute victory.

Bidding to become the first woman since Lindsay Davenport in 2005 to successfully defend Stuttgart, Sharapova will face either 2011 French Open champion Li Na or American qualifier Bethanie Mattek-Sands in Sunday’s final.