Hello and welcome to LIVE updates of the first singles match of Day 4 at the 2020 ATP World Tour finals. It’s 2018 winner, Alexander Zverev against tournament debutant, Diego Schwartzman in Group Tokyo 1970. Both players lost their opening matches and cannot afford defeat here if they are to realistically keep their hopes of making the semis alive.

Zverev's win means Djokovic will advance to the semi-finals if he beats Medvedev in straight sets tonight. Medvedev will go through with any win.

GAME, SET AND MATCH! – ZVEREV 6-3 4-6 6-3 SCHWARTZMAN. Diego can’t pose the serve-out question and dumps a tight forehand into the net to hand the match to Sascha on his first match point. The German lost his way slightly in Set 2 but recovered in the decider to earn the victory in two hours and 11 minutes. He remains in the hunt to make the last four but will meet Djokovic next.

ZVEREV 6-3 4-6 5-3 SCHWARTZMAN. Sascha maintains his grip on this final set with another dominant service game. He's one away from victory now.

Some news off the court...

ZVEREV 6-3 4-6 4-3 SCHWARTZMAN. A huge roar from Diego. He refuses to give in here. It looked like he was done at 15-40, but he doesn’t want to touch rackets at the net just yet. He wriggles out of danger from deuce to stay alive for now.

ZVEREV 6-3 4-6 4-2 SCHWARTZMAN. Sascha consolidates with a solid hold to 15. He can see the finish line again now, but needs to stay in the zone.

BREAK! – ZVEREV 6-3 4-6 3-2 SCHWARTZMAN. In answer to my previous question – it’s Diego. The Argentine looks to his team in anguish as he hooks a tame attempt on the stretch into the net. He’s forced into sliced defence as Zverev dictates the point to snare a couple of break opportunities quite brilliantly. The German then clinches the game with a wonderful angled volley on the move.

ZVEREV 6-3 4-6 2-2 SCHWARTZMAN. Zverev ensure he stays toe-to-toe with another clinical love hold. Looks like the calm before the storm. Who is going to blink first?

ZVEREV 6-3 4-6 1-2 SCHWARTZMAN. Still with serve in the early sparring of this decider. Schwartzman is a completely different proposition now.

ZVEREV 6-3 4-6 1-1 SCHWARTZMAN. Mini alarm bells would have been ringing in Zverev’s head at 0-15 but he recovers splendidly to reel off the next four points and level matters with ease.

ZVEREV 6-3 4-6 0-1 SCHWARTZMAN. The momentum stays firmly with the world number nine. He blitzes a wrong-footing forehand down the German’s left wing to claim a hold to 30 to kick off the deciding set in style.

SET! – ZVEREV 6-3 4-6 SCHWARTZMAN. Zverev smashes a ball into the stands in frustration. He gets a warning, but he’ll be more concerned that El Peque has levelled the match. The Argentine really found his return game to tee up double set point. A blistering ace saved one, but Schwartzman got a big serve back on the second and duly forced an error just long by staying in the rally. Super stuff from the Argentine.

ZVEREV 6-3 4-5 SCHWARTZMAN. Diego is showing some of the form that saw him make such a late charge to make it to these finals. He ghosts into the net to put away a smart volley before unloading a crosscourt forehand winner on his way to a convincing hold.

ZVEREV 6-3 4-4 SCHWARTZMAN. No drama this time around. Zverev rampages through a quick-fire love hold. What a contrast to his last service game!

ZVEREV 6-3 3-4 SCHWARTZMAN. There’s a roar of delight and a pump of the fist from the Argentine as he nudges the board in his favour with a fine hold. He’s kept plugging away and when his opponent’s level has dipped, he’s made sure he has been ready to take advantage.

BREAK! – ZVEREV 6-3 3-3 SCHWARTZMAN. Just when it looked like Zverev had focus and control, he throws in an awful service game. Schwartzman has three shots at a break and earns the reprieve on his second. All square in Set 2.

ZVEREV 6-3 3-2 SCHWARTZMAN. There’s certainly been a sense of déjà vu about this for Schwartzman. Not only in being largely second best on an indoor court against Zverev once again, but also in the way this match has followed a similar pattern to his opener against Djokovic. He had the early break there and fell away. Now he’s trying to stop that happening here, but he’s having to put in some serious shifts just to hold. He gets it done under pressure from deuce here to stay in contention.