The big serving Aussie was dominant for much of the contest against the defending champion winning 6-3, 6-4.

It was his first straight sets victory in the tournament after again having to go to a third set tie-breaker to get past Portugal’s Gustao Elias early Saturday morning.

Groth broke Smyczek serve to win the 10th game of the second set with a copy book backhand, forehand play at the end of a baseline rally.

Groth saved four match points across the final two sets against Elias on Saturday just to reach the Knoxville semi-finals. 

Groth shot a set and 4-1 up over Smyczek but the American issued a late challenge and managed to draw level through eight games.

That came after the 27-year-old Aussie had produced five double faults in four service games.

Groth even had to wrestle his way out of 30-all in the ninth game to push 5-4 ahead before a wayward Smyczek service game left the door open.

The former Albury junior will now play French World no.61 Adrian Mannarino for the title early tomorrow morning.

He won his only prior clash with 26-year-old in straight sets, although that was seven years ago and at Futures level.

The left handed second seed, who made the third round of the US Open earlier this year has breezed through this tournament, winning his semi-final 6-0, 6-4.

The match will be streamed live through the ATP Challenger Tour website about 6.30 am tomorrow.