SHANGHAI, China (AP) — Novak Djokovic maintained his dominance in China by holding off Juan Martin del Potro 6-1, 3-6, 7-6 (3) yesterday to capture a second Shanghai Masters title and extend his winning streak in the country to 20 consecutive matches.

The Serb completed a back-to-back sweep of titles at the China Open in Beijing and the Shanghai Masters for the second straight year. He’s now captured seven titles overall in China — the most he’s won in any country.

Djokovic had to overcome a strong challenge from del Potro, who fended off two match points late in the third set, but couldn’t put any pressure on Djokovic’s serve down the stretch and appeared to fade in the tiebreaker.

“He’s a big fighter. All the way up to the last point, I don’t know if I’m going to win the match,” Djokovic said. “His forehand is one of the best in the game, one of the best I’ve ever played against. It’s a huge weapon and once it’s on, it’s very dangerous.”

For Djokovic, the title has added significance coming just days after he relinquished his top ranking to Rafael Nadal, who lost to del Potro in the semi-finals. He can’t retake the top spot this week, but Djokovic has been focused on finishing the year strongly to stay within striking distance.

“Considering the rankings, I put myself in a better position right now with back-to-back wins,” the six-time Grand Slam winner said. “But the fact that if I would win, I would put myself in a better position, did not affect my motivation. My motivation is there always, especially when I’m playing finals of such a big event.”

It was a tough loss for del Potro, who was trying to win his maiden Masters title at his third attempt. He was coming off a title last week at the Japan Open in Tokyo, and he got his first win over Nadal in four years in the semi-finals in Shanghai.

Del Potro overpowered Nadal so completely in that match, the Spaniard later said: “Very few times I played against a player with a level like today.”

Del Potro served notice, however, that he’s fully fit and confident again after a wrist injury nearly derailed his career after his breakthrough win at the 2009 US Open.

He’s back up to the number five ranking — his highest in three years — and has beaten Djokovic, Nadal and Andy Murray this year. He also scored one of the biggest wins of his career over Djokovic at the London Olympics last year, where he beat the Serb in the bronze medal match.

The match looked like it might be a runaway win for Djokovic early on as he raced out to a 5-0 lead in the first set by dictating play with precise groundstrokes and keeping a sluggish del Potro on the defensive.

But the momentum shifted in the second set when del Potro began connecting on his serve and cracking the same forehand winners he used to sweep Nadal off the court in straight sets in the previous round.

He broke Djokovic to take an early lead, then played a magnificent game to save three break points to hold for 5-2 before closing out the set.

The Argentine appeared to tire slightly as the third set wore on. During one changeover, the chair umpire, Damien Dumusois, warned him that he needed to speed up play between points. “Even after a long rally?” del Potro asked, looking up wearily. Dumusois nodded yes.

Djokovic had two match points on del Potro’s serve at 4-5 in the set, but the Argentine saved them both. The Serb then pulled away in the tiebreaker by hitting a forehand winner to finish off a 24-shot rally to take a 4-2 lead, leaving del Potro unable to manage another comeback.