Roger Federer has strategically gone back to the slice.

Federer defeated Alexander Zverev 7-6(6), 5-7, 6-1 to be the first player to advance to the semi-final stage of the Nitto ATP Finals after a masterful performance at The O2 on Tuesday night.

If you caught just one sentence of his post-match press conference, all you needed to hear was this: “I think I was able to stay the course and use my slice quite effectively, then try with variation and go into his forehand,” Federer said.

Federer is back to hitting a lot more slice returns and slice backhands in London because the court conditions and the opponent simply dictate it.

Federer Returns

The Federer renaissance in 2017 has been built around coming over his backhand return, but that’s not what got him over the line against Zverev on the quicker hard court in London. Overall, Federer hit a dominant 64 per cent of his returns as a slice, flattening out his return only 36 per cent of the time. This was in stark contrast to Zverev, who came over 95 per cent of his returns, hitting only five per cent as a slice.

This clever strategic adjustment from Federer reduced his return speed (which is not always a bad thing), lowered the rally when he returned shorter, and also provided less power to be immediately used back at him.

Average Return Speed

First Serve

• Federer 50 mph / Zverev 62 mph

Second Serve

• Federer 59 mph / Zverev 73 mph

Federer put a commendable 70 per cent of his first serve returns back in play, and 84 per cent against second serves. He attacked his returns much more with his feet than with his hands.

Average Return Contact Point

First Serve

• Federer 0.9m behind baseline / Zverev 1.8m behind baseline

Second Serve

• Federer 0.4m inside baseline / Zverev 0.7m behind baseline

Federer’s return tactics could even be seen in the return height over the net. Against first serves, his slice return generally floated a little higher to increase the consistency and depth of the return. Federer’s first serve return height had a net clearance of 1.34m, which was slightly higher than Zverev’s 1.24m.

Variation To The Forehand

Once the rally began, Federer still went to the slice a lot, hitting 25 per cent of all groundstrokes with backspin, and 75 per cent with topspin. As he mentioned in his press conference, Federer wanted variation against an opponent who typically brings the same aggressive look on every shot. Zverev hit a dominant 96 per cent of his groundstrokes with topspin, which was not always comfortable to do against Federer’s low slice backhands.

Federer constantly targeted Zverev’s forehand throughout the match, directing 55 per cent of his own forehands to the outer third of the court, to Zverev’s forehand wing, just 11 per cent down the middle and 34 per cent out wide to the backhand in the Ad court.

Federer also hit 30 per cent of his own backhands straight down the line to Zverev’s forehand, trying to stretch him out wide, and also to rebound the ball back crosscourt to Federer’s forehand.

A main reason Federer targeted Zverev’s forehand in rallies is that the tall German tends to hang back deeper in the court when hitting it. Overall, Zverev hit a considerable 35 per cent of all forehands standing in the deep zone of at least two metres behind the baseline, but just 22 per cent of all his backhands were struck from back there.

Federer hit 157 forehands (57 per cent) and 120 backhands (43 per cent) for the match, while Zverev was basically dead even, hitting 135 forehands and 134 backhands.

As great as Federer is, he still views himself as the second most important person on the court. His strategy is primarily dictated by the person standing opposite him.