The United States put one foot in the semi-finals of the CONCACAF Nations League after a late flurry of goals secured a nervy 3-0 win over Trinidad & Tobago on Thursday.

Ricardo Pepi, Antonee Robinson and Gio Reyna scored in the final 10 minutes in Austin, Texas, to leave Gregg Berhalter's side firmly on course for a place in the last four.

The Americans can book their place in the semi-finals -- and a ticket to next year's Copa America taking place in the United States -- when they head to Port of Spain next Monday for the return leg.

But the US will prepare for the second leg taking nothing for granted after struggling to impose themselves on a Trinidad & Tobago team who were reduced to 10 men following Noah Powder's first-half dismissal.

"It was just one of those days where it felt like nothing was going in," Robinson said after the win. 

"I feel like we created more chances, but I think we'll be disappointed -- we should be putting more past them with 10 men really.

"But 3-0 is still a decent lead going into the next leg, and hopefully we'll have a better performance next time."

It looked for long periods as if the "Soca Warriors" would hold on to secure a draw against the Americans, who failed to register a shot on target in the first half.

However a tactical switch by Berhalter in the second half, moving Borussia Dortmund's Reyna into a more central role, paid off as the US began to dominate.

The Americans looked ready to make a breakthrough in the 60th minute when Daniel Phillips brought down Weston McKennie in the penalty area.

Jamaican referee Oshane Nation pointed to the spot but after an intervention from the VAR the penalty award was overturned.

The deadlock was finally broken in the 82nd minute when good play from Reyna saw the ball worked to Fulham defender Robinson on the left flank.

Robinson whipped in a low ball and Pepi was waiting at the near post with the deftest of flicks to finally beat Trinidad goalkeeper Denzil Smith.

Four minutes later Robinson doubled the lead with his first international goal, his well-struck shot from the edge of the area taking a deflection on its way into the net.

As relief coursed around the Q2 Stadium, Reyna added a third on 89 minutes, playing a neat one-two with Folarin Balogun before finishing to give the Americans a 3-0 advantage heading into the second leg.