The fourth and final match on Grandstand is a big one. It pits No.6 seed Dominic Thiem with 2009 US Open winner, Juan Martin Del Potro.

BREAK! - THIEM 4-0 DEL POTRO. Something isn't right with Delpo. He's really struggling out there. He slaps a terrible crosscourt forehand attempt into the net to weakly hand the double break to his opponent. Thiem racing towards a one-set lead.

Later on Arthur Ashe... this guy....

THIEM 3-0 DEL POTRO. A delicious backhand winner down the line sees the Austrian consolidate with real style. Plenty of food for thought for JM as he takes his seat.

BREAK! - THIEM 2-0 DEL POTRO. A really loose service game from Delpo. The errors leak off his racket as he gifts Thiem a fabulous start with a tight backhand into the net on the second of three break points.

THIEM 1-0 DEL POTRO. A tricky opener for Thiem. He fends off an early break point and survives a lengthy stand-off from deuce to hold after seven minutes. If that's a sign of things to come, we could be here for some time... #epictussle

Thiem will serve first...

The winner of this will face Roger Federer or Philipp Kohlschreiber in the quarter finals.

The players met at the same stage of this tournament last year with Delpo leading 6-3 3-2 when Thiem was forced to retire. Their only other showdown was at the 2016 Madrid Masters where the Argentine triumphed in straight sets.