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Roger Federer got the better of Stan Wawrinka in the semi-finals of the Barclays ATP World Tour Finals for the second straight year.

Brain Game: Federer's Tactical Change

Dig into the stats to learn why Roger Federer beat Stan Wawrinka on Saturday night

Roger Federer is our sport’s most colourful chameleon. His adaptive skills were on full display Saturday night in his 7-5, 6-3 victory over Stan Wawrinka, to move through to the final of the Barclays ATP World Tour Finals in London.

Federer is a master of every tactical maneuver, equally adept at staying back, coming forward, altering spin and power, managing time, and possessing the uncanny ability to “feel” what the court, the ball, the conditions and the opponent provide him.

Federer only came to the net nine times (winning six) against World No. 1, Novak Djokovic, earlier in the week, simply because he calculated that heavy groundstrokes were the best pathway to secure victory in that moment, on that night.

Last night against Wawrinka, he strategically changed his colours, swarming the net in an effort to blunt his opponent’s thumping groundstroke speed.

Federer came forward to the net 32 times against Wawrinka, playing only one extra game against his Swiss opponent than Djokovic.

Federer won an extremely high 75 per cent (24/32) at the net, pressuring Wawrinka with his court position, and rushing Wawrinka’s groundstroke preparation. Wawrinka only managed to get to the net three times for the whole match, highlighting just how dominant Federer was at owning the front of the court.

Infosys Match Insights uncovered a hidden strength of Federer’s forward movement - getting closer to the net to create more angle for the volley, and visually shrinking the court for the opponent’s passing shot.

Federer hit 27 volleys for match, mixing in serve and volley and approach plays, and amazingly only hit two volleys standing behind the service line. That’s a remarkable discovery, and you can only imagine how difficult he is to pass from such perfect court position.

Federer’s serve is a great enabler of his forward movement, as it continually elicits short balls for him to devour.

Federer hit 100 shots as the first shot after his serve, with 66 of them being struck inside the baseline, 33 within two metres behind the baseline, and just a lonely one further back than two metres behind the baseline.

When returning, it was a tougher ask to immediately move forward, as he had to initially negate the strength of Wawrinka’s powerful serve, and thumping first groundstroke. Federer made contact with the ball 22 times inside the baseline with his first shot after the return, 51 times within two metres of the baseline, and 27 times more than two metres back.

Once a rally was established, Federer hit 53 per cent forehands for the match and 47 per cent backhands, better than Wawrinka’s even 50/50 ratio.

But a deeper look at Wawrinka’s forehand performance uncovered that he only hit 11 run-around forehands standing in the Ad court for the match, which is normally a primary baseline strategy.

Wawrinka Return Location

The pressure of Federer’s constant forays forward forced Wawrinka to drastically alter his return location, but all it did was simply take him out of his comfort zone.

Federer won 76 per cent (31/41) of his first serve points, and an extremely high 65 per cent (15/23) of second serve points.

Against Rafael Nadal in the round robin draw, Wawrinka averaged standing 2.95 metres (9.7 feet) behind the baseline to return second serves, but he was only 27 centimetres (0.9 feet) behind the baseline against Federer.

Wawrinka was forced to move forward and take the second serve return earlier to try and immediately get the ball down to Federer’s feet, or rebound it deep near the baseline with the threat of an imminent net attack.

Federer averaged standing 1.4 metres (4.6 feet) inside the baseline returning Wawrinka’s serve, successfully pressuring Wawrinka into only winning a lowly 42 per cent (10/24) in this key tactical arm wrestle.

Federer will now play Djokovic in this afternoon’s final, and the tactics that worked earlier in the week may have to be drastically altered to defeat the World No. 1 on Sunday. Fortunately, Federer is ready to change colours in the blink of an eye.