Roger Federer edged closer to regaining world number one status as he strolled into the Stuttgart Open semi-finals with victory over Guido Pella.

The eight-time Wimbledon champion looked rusty in the opening set of his match with Mischa Zverev on Wednesday, but eventually found his rhythm to progress in three.

Getting past Pella was a much more straightforward task for the top seed as the graceful Federer cruised to a 6-4 6-4 victory in 66 minutes.

Federer is now one win away from reclaiming top spot in the rankings from Rafael Nadal, the 20-time grand slam winner only needing to reach the final to climb to number one.

From the outset Federer looked much more assured than he did against Zverev, the appearance of his elegant backhand in game seven a sure sign his levels were high.

That shot down the line proved too good for his Argentine opponent and brought up the first break points of Friday's clash – Pella saving the first before Federer converted a crisp cross-court forehand.

Having consolidated the break, Federer quickly moved a set ahead with a service game to love, Pella failing to even get a glimmer of an opening on his rivals serve.

Pella's resistance had been dented and Federer wasted no time piercing another hole in his defence, the world number 75 falling 2-0 down at the start of the second set.

Federer continued to serve with power and precision, Pella only able to apply any kind of pressure when trailing 4-3.

His first break points of the match came with Federer serving for the win, the 36-year-old swatting them away with ease before the return of that trademark backhand sealed a 14th consecutive win on grass and a last-four berth.