The scoreboard showed Maria Sharapova sinking bleakly in a 4-1 third-set hole, but her body language told a different story. Pounding her clenched left fist against her thigh and stalking the baseline in a predatory posture, Sharapova was committed to the comeback cause.

The eighth-seeded Russian regained her range, took the fight to Christina McHale, and reeled off five straight games to complete a 6-1, 4-6, 6-4 victory that sent her into the Madrid round of 16 for the fourth time.

It wasn't easy and it wasn't pretty. But the result reinforced Sharapova's willingness to do the dirty work—and raise her intensity at critical moments—in digging out a demanding match that spanned 2:18 and took some severe twists along the way.

The Stuttgart champion came out punishing the ball, confining McHale to chase mode for much of the first set. Blistering shots into the corners, Sharapova won five consecutive games to bulldoze through the opening set in 32 minutes. McHale's forehand is her best weapon, but Sharapova neutralized it by banging her backhand cross-court, dragging the American wide to clear the court and create space for her backhand down the line. The match followed a familiar script, as Sharapova had not surrendered a set to the New Jersey native in three prior meetings—including a 6-1, 6-2 shellacking at the same stage in Madrid last May.

Gaining little traction in baseline rallies and forced to defend her weaker backhand wing, McHale made a tactical adjustment: She stepped in and began playing her forehand inside-out to Sharapova's two-handed backhand to set up her forehand down the line. McHale, who served 65 percent compared to 42 percent for Sharapova in the second, won 15 of 19 first-serve points in a set that began with nine straight service holds.

The adjustment paid off. When Sharapova's backhand down the line missed the mark, the world No. 56 had a set point. A frenetic exchange followed. Stretched out, Sharapova's sliding cross-court backhand missed the mark, and McHale had won her first set against the four-time Grand Slam champion.

The underdog could smell the upset shortly after her electric running forehand down the line coaxed a backhand error from her opponent. When Sharapova misfired on a forehand, McHale had the break and a 3-1 lead. She backed up the break at love, slamming a forehand winner for 4-1. The upset was now in sight.

Short-term memory loss is a prerequisite for elite players, but Sharapova's coach, Sven Groeneveld, urged his charge to compete with more energy, use the "backhand body serve" to jam her opponent, and rely on her recall of past battles to ignite her third-set charge.

"It's one break, you'll get it back," Groeneveld insisted while a stoic Sharapova stared straight ahead during the changeover, chomping on a banana. "You've done it a thousand times, you'll get it back...Turn your shoulders and step in."

McHale's moment of truth came while serving at 4-2, 40-30. Sharapova crunched a backhand winner down the line—then McHale blinked, spinning a double fault into net and a netting backhand. Two games later, Sharapova broke at love for 5-4, and sealed the comeback by slamming her first ace of the set down the T.

Since her second-round loss at Indian Wells to qualifier Camila Giorgi, Sharapova has won 11 of her last 12 matches. The 2013 Madrid runner-up will face either Samantha Stosur or Spaniard Garbine Muguruza for a quarterfinal spot.