Mackenzie McDonald reaches maiden ATP final at Citi Open Washington with superb win over Nishikori

Mackenzie McDonald will be involved in his first ATP final on Sunday after outlasting Kei Nishikori 6-4, 3-6, 7-5 at Citi Open Washington.

A terrific tie which saw a close affair from the end of the second set onwards, it was McDonald who outlasted the Japanese ace who's welcome return to form continues.

As is the case for the American who himself has battled his fair share of injuries but will head back towards his career best ranking on Monday. He will face Jannik Sinner tomorrow who outlasted Jenson Brooksby earlier but will it be the Italian prospect or the American ace on home soil who claim a maiden ATP 500 title.

McDonald edged through the opening set 6-4 to go one away from the final but it wasn't all she wrote for Nishikori.

It was a positive start in the second set for the Japanese ace but he began to look laboured as McDonald rose to the challenge in style winning three games on the bounce with the serve to make it 4-2 and surge towards the finishing line.

But McDonald himself started to capitulate from 40-0 up to claim that lead and Nishikori was sat at 3-3 instead of potentially on the brink.

This reverted again with Nishikori leading 4-3 and heading towards potentially a final set. He brought up another break point as he started to up the pace and momentum in his favour.

McDonald did buckle to break once more and go one game away from a final set which Nishikori did convert on his serve.

Nishikori looked more settled and was forcing the errors from McDonald who handed him two break point opportunities.

But under pressure, McDonald eventually got the service hold to hand the initiative back to Nishikori.

Nishikori was looking for an early break of serve but it wasn't forthcoming as McDonald went 2-1 up and this theme continued with long games but McDonald edging it 3-2 with a break likely proving pivotal.

McDonald got a break point opportunity but this was snuffed out by Nishikori with a dropshot and again Nishikori was serving for a 3-3 level game.

A rapid service game from McDonald saw him lead again at 4-3 as the hard fought nature of the deciding set continued. Nishikori continued to battle and levelled it once more at 4-4.

A double fault threatened to derail McDonald who handed Nishikori a break point opportunity once more but the former showed guts to evade that and steady himself at 5-4 up.

Once again, Nishikori held serve but just as it looked like the duo would tire they produced an epic rally won by the American who was serving for 6-5 with a break still needed which he sealed with a stunning forehand winner just on the line.

McDonald looked like he was preparing himself for a tiebreak but suddenly the game turned in his favour and he was allowed a match point which he sealed after an error from Nishikori sending it into the net.