CINCINNATI, OH, USA - Reigning Wimbledon champion Simona Halep made a triumphant return from injury on Wednesday, rallying from a set down to defeat rising Russian Ekaterina Alexandrova, 3-6, 7-5, 6-4 and reach the third round of the Western & Southen Open.

GALLERY: From Jankovic to Bertens - A Decade of Cincinnati Champions

"I got the confidence game by game, even if she was leading me," she said in her post-match press conference. "I still thought that there is a chance to win, and I have just to fight."

Halep was a game from defeat in the second set but showed her signature fighting spirit to outlast her big-hitting opposition after 124 minutes on Center Court.

Halep was playing her first match since having to retire in the Rogers Cup quarterfinals against Marie Bouzkova, citing a left lower leg injury, while Alexandrova was fresh off a tight two-set defeat to 23-time Grand Slam champion Serena Williams at that same tournament

Feeling physically fit, the Romanian gamely saved two break points early in the opening set and held four on Alexandrova's serve in the very next game - three in a row at 0-40 - before her unseeded opponent caught fire.

"She kept the rhythm and the level of her game very high today the whole match. So I needed something extra to finish it to be well."

Striking 14 winners to just three from Halep, Alexandrova held serve and rolled through seven of the next eight games to take a set and break lead on the No.4 seed.

MORE: 'I'm living the dream' - Halep sets sights on US Open goals

Though Halep soon leveled the second set and two games apiece, what followed was a tense exchange of service holds as Alexandrova continued to press from the baseline with booming groundstrokes, ultimately inching to within three points of the upset.

Dropping just two points in the final three games, Halep suddenly turned the tables on the Russian, who threw in some untimely misses into the net, and forced a deciding set with an emphatic hold to love.

"I knew that she's gonna play really, really well, and she did. But I didn't give up, and I'm very pleased with that."

But the two-time Grand Slam champion was far from home free, even as she broke first in the fifth game. In a marathon that followed, the Russian engineered a third break point opportunity with an inside-in backhand winner and followed it up with another on the same side to immediately draw level and move ahead with some big serves.

Moving head to 4-3, Alexandrova struck a few more powerful returns to open up a 0-30 lead. With a forehand winner of her own, Halep had the momentum once more, winning eight points in a row to run away with the match.

Up next for the Romanian is either former US Open finalist and No.16 seed Madison Keys or Daria Kasatkina.

"Two very different styles," Halep smiled. "Keys is hitting really strong, the ball, and is playing flatter. A lot of power. Kasatkina is the other way. She has a lot of topspin. She moves the ball a little bit more on the court.

"So it's difficult and different plans for them. I will think about it a little bit later today after I will see against who I play."