Leona Maguire and Lucas Glover had to split $185,000 after they slipped to tied sixth behind New Zealand's Lydia Ko and Australia's Jason Day in the Grant Thornton Invitational in Florida.

Just two shots off the lead heading into the final round battle for a $1 million top prize, the Irish-American duo paid for a slow start and carded a 68 in the modified fourballs to finish four shots behind the winners on 22-under par.

Scores

Day and Ko shot a six-under 66 to win the $1 million team prize one stroke on 26-under from Canadians Brook Henderson and Corey Conners, who closed with a 63 at Tiburon Golf Club in Naples.

With both players teeing off and then playing their partner's ball from there, Maguire and Glover started with six pars before picking up four shots in the last 12 holes.

But they had to settle for joint sixth with Lexi Thompson and Rickie Fowler (66) as they were caught in a scoring stampede on the final day.

Sweden's Madelene Sagstrom and rookie sensation Ludvig Aberg came home in eight-under 28 as they made ten birdies and an eagle in a 12-under 60 to finish third on 24-under.

"Personally, I've struggled a little bit with foursomes, both in Solheim Cups and in general," Sagstrom said. "I think it's kind of hard when you really don't want to screw up someone else.

"I felt comfortable today. I've been driving the ball fairly well this week, so I knew I was going to keep him in play from the tee, and then he's such a great golfer, so I knew we were going to have a lot of chances."

Denny McCarthy and Megan Khang (65) tied with Nelly Korda and Tony Finau (67) for fourth on 23-under.

Day and Ko turned in two-under before closing out the victory with four back-nine birdies.

"It was kind of weird because it felt like the most stress-free win because I just knew that she was going to step up in the end, which was fantastic," Day said. 

"I mean, it was just it was a fun week. I think having the two tours join this week was a fun way to finish the year, and I'm hoping we get to do it for a very long time."

Ko added: "I think this has just been a great start for the two tours coming together and having a mixed event and I really hope that this is something that continues for a long time."

Meanwhile, Jim Furyk's Team USA won the inaugural World Champions Cup at The Concession in Florida with 222 points, edging out Ernie Els' Internationals by just two points.

Darren Clarke's Team Europe was third with 208 points.