Lionel Messi inspired Inter Miami to come back from two goals down to beat Cincinnati 5-4 on penalties after their thrilling US Open Cup semi-final ended 3-3 after extra-time.

Miami, who won the Leagues Cup on penalties against Nashville on Saturday, are now one win away from their second trophy since Messi joined the club last month.

Cincinnati are top of Major League Soccer's standings while Miami are bottom but the Florida team are now a very different side to the one which was winless in their 11 league games before the arrival of the Argentine.

The enthralling unbeaten run of Miami, since the signing of Messi and Spanish pair Sergio Busquets and Jordi Alba, looked to be coming to an end in Ohio against an impressive Cincinnati side.

Inter trailed 2-0 with 22 minutes remaining before the Argentine delivered two perfect assists to striker Leonardo Campana to take the game into extra-time.

Messi's compatriot Luciano Acosta put Cincinnati ahead in the 18th minute and American striker Brandon Vazquez doubled the home side's lead with a fine strike from the edge of the box in the 53rd minute.

But in the 68th minute, Messi whipped in a free-kick from the left which was headed home by Campana to breathe some life into what had been a tired display from Gerardo Martino's side.

Then in the seventh minute of stoppage time Messi, from deep on the left, swung in a ball to Campana at the back post again and the Ecuadoran forward angled home his header to force extra-time.

Miami went ahead in the first period with Benjamin Cremaschi sliding an excellent pass into the path of Josef Martinez and the Venezuelan made no mistake with a clinical finish.

But Cincinnati bounced back in the second period with Japanese winger Yuya Kubo firing a right-foot shot into the far corner past the diving Drake Callender.

The teams were at 4-4 in the shoot-out when Callender saved Nick Hagglund's penalty for Cincinnati and Cremaschi converted to book Miami's place in the final.

The 18-year-old Miami-born Cremaschi, whose parents are Argentine, was congratulated by Messi after his match-winning spot kick.

"I'm living a huge dream," he told CBS Sports, "Sometimes I sit down and really think about the position that I'm in and it's incredible, I never believed I was going to be in the spot I am in now," he said.

Miami will face the winners of Wednesday's other semi-final between Houston Dynamo and Real Salt Lake.