Maria Sharapova remains on course for a first WTA title since returning from a drug ban after beating Peng Shuai in straight sets in the semi-finals of the Tianjin Open. The five-time grand slam champion needed just 78 minutes to beat the No3 seed Peng 6-3, 6-1 and book a final date with the world No 102, Aryna Sabalenka of Belarus.

Sharapova, a tournament wildcard, made the perfect start by breaking Peng’s serve in the first game of the match and closed out the set with another break. Peng had held her own for much of the opening set but the former world No1 broke early in the second and completed a comfortable win.

Sharapova, who made her comeback in April, has advanced to her first WTA final since May 2015 without dropping a set. The 30-year-old will meet the teenager Sabalenka in Sunday’s final after the Belarusian defeated Italy’s Sara Errani 6-1, 6-3.

Meanwhile, Rafael Nadal will meet Roger Federer in the final of the Shanghai Masters after the Swiss second seed fought back to defeat Argentina’s Juan Martín del Potro. Del Potro had taken the first set but was unable to make it through to the final as Federer won 3-6, 6-3, 6-3 to set up a meeting with Nadal.

Del Potro looked on course to record an upset as he claimed his only break point of the first set to move ahead in the contest. However, Federer proved too strong as breaks in the next two sets earned him victory and set up a clash with the only player who leads him in the ATP rankings.

Nadal celebrates his victory over Cilic in Shanghai. Photograph: Lintao Zhang/Getty Images

The match hinged on the second set as Federer failed to convert four successive break points at 3-2 up but he claimed his next chance to swing the contest his way. With Del Potro unable to set up a break point in either the second or third sets, Federer was able to progress in one hour and 58 minutes to face Nadal for a fourth time this season. He holds a 3-0 advantage over his rival.

Nadal had earlier reached his 111th career final and 10th of the year with a 7-5, 7-6 (3) victory over the big-serving Croatian Marin Cilic. The Spaniard, who lost to Nikolay Davydenko in his only previous Shanghai Masters final appearance in 2009, hit 23 winners and benefited from 40 unforced errors by his opponent.

Cilic came under pressure early on as he had to save six break points in his first two service games before hitting back as he went on to waste three set points. Nadal was able to hold serve to make it 5-5 and then break in the next to lead before serving out for the set in 67 minutes.

Breaks of serve were exchanged midway through the second set and Cilic kept himself in the contest with a big forehand winner down the line as Nadal served for the match at 5-4. But when the set went into a tie-break Nadal clinched the match with a service winner in a little over two hours to take his winning run to 17 matches.