Off pace worked off the charts for David Goffin at The O2 on Friday afternoon. Goffin defeated Dominic Thiem 6-4, 6-1 at the Nitto ATP Finals to advance to the semi-final stage of the season finale against Roger Federer on Saturday. Read & Watch Match Report

It actually started badly for Goffin, who found himself struggling at 0-3, 0/15 in the early stages of the match. The Belgian then went on a tear, winning 15 straight points to shock Thiem and light up the packed house in London.

How did Goffin do it? By delivering a steady of diet of exactly what Thiem didn’t like to devour - slower balls that completely disrupted Thiem’s rhythm and timing.

Quite simply, Thiem loves for the ball to come to him. He wants to stand deep in the court and utilise his opponents’ power right back at them.

Goffin failed to oblige.

Instead, he upped his consistency, lowered the rally speed, and enjoyed extracting 27 unforced errors from the exasperated Austrian.

By Thiem’s own admission, he craves power and spin in the rally. “It’s not easy, the surface, for a player who plays a lot of topspin,” Thiem said post-match. It seemed highly unlikely that Goffin would dominate this winner-take-all encounter, given that the Belgian lost 6-0, 6-2 to Grigor Dimitrov at the Nitto ATP Finals just two days earlier.

From serving, to returning, to trading blows from the back of the court, Goffin purposely hit the ball slower so that Thiem didn’t have the ammunition to fire directly back at him.

It was a bold move that took courage and conviction to execute. It’s not easy to play slower, because you risk getting blown off the court. It’s not easy to provide your opponent something juicy to hit, unless you clearly understand that a slower ball is sometimes tougher to connect with than a more powerful delivery.

Consider the following eight areas of the match where Goffin generally avoided going toe-to-toe with Thiem in speed of shot.

THIEM vs. GOFFIN: SPEED OF SHOT

To what lengths was Goffin willing to go to slow down the ball and give Thiem nothing to work with? Consider this…

Serving at 6-4, 4-1, deuce, Goffin hit an 86 miles per hour first serve out wide that clipped the net and sailed long. His second serve was faster, at 90mph. Goffin’s number one strategy at this advanced stage of the match was to get Thiem to play out in front of the ball and miss.

A secondary theme of the match was Thiem’s low first-serve percentage. He is averaging 59 per cent first serves in 2017 coming into London, but only managed to put a lowly 43 per cent first serves in play against Goffin. Combine that with the 36 per cent (10/28) second-serve points won, and it’s no wonder Thiem felt so out of sorts in the match. He simply had nothing to lean on, to find a pathway to victory.

This is the third straight time Goffin has defeated his higher-ranked opponent, and now enjoys a 7-3 FedEx ATP Head2Head series lead over Thiem. Hitting through an opponent is easy. Letting your opponent hit themselves out of the match requires supreme confidence in the game plan.

Once again, Goffin nailed it.