The United States conjured up some magic moments on the 18th green to fight back in Friday's foursomes and hold the Internationals to a 6.5-3.5 lead after Ernie Els' team threatened to deliver a decisive blow at the Presidents Cup.

The Americans, trailing in all five matches at one point, dug deep at Royal Melbourne to share the day two honours, with captain Tiger Woods and his playing partner Justin Thomas leading the way once again.

Woods and Thomas were the only pair to score for the United States in the opening fourballs on Thursday and returned to claim a vital point in a 1-up win over Hideki Matsuyama and An Byeong-hun.

Thomas rolled in a 17-foot putt on the 18th to secure the win and celebrated wildly before being wrapped in a bear-hug by Woods.

"I'm speechless, I've been fortunate to make a lot of big putts and hit a lot of big shots," said Thomas.

"But to do it with my captain and unbelievable team mate to win the match, hopefully turn the tide of this Presidents Cup is awesome."

Woods added: "We clawed our way back and JT steps up there and pours this thing in at the last hole and it gives me absolute chills, man. Absolute chills."

Earlier, Patrick Cantlay, teamed up with Xander Schauffele, rolled in a 14-foot birdie putt on the 18th to claim a 1-up win over Adam Hadwin and Joaquin Niemann.

Rickie Fowler capped the stirring U.S. fightback with a clutch putt for par on 18 to clinch a half-point against Cameron Smith and Im Sung-jae.

Until that final hour, the Internationals appeared set to extend their lead and give themselves a huge chance of ending a run of seven successive losses in the event.

Still, Els' team are in rare air, having not led the competition after day two since 2005.

Els said his players now knew what they were up against.

"This was probably good for them, showing what can happen the last couple holes," said the captain.

"My guys learnt a lot from this afternoon."

Adam Scott and Louis Oosthuizen got the ball rolling for the Internationals as they came back from two holes down to secure a 3&2 win over Dustin Johnson and Matt Kuchar.

It was Johnson's second successive loss after he and Gary Woodland were trounced 4&3 by Abraham Ancer and Oosthuizen in the fourballs on Thursday.

Mexican debutant Ancer and Australian Marc Leishman then combined to continue Patrick Reed's forgettable Presidents Cup as they swotted aside 'Captain America' and Webb Simpson 3&2.

Fiery Texan Reed, heckled by the crowds after his controversial bunker penalty last week, made a defiant "shovelling" gesture at the gallery on the 11th but will need to dig deep to lift himself out of a 2-0 hole for the event.

Reed will have a chance to do so early on Saturday, with Woods giving he and Simpson another chance in the morning fourballs.

The United States will have to attack the morning without talisman Woods, however, who has elected to sit out the fourballs and lead from the sidelines.

Woods may return for the four foursomes matches in the afternoon, however.

With eight points up for grabs, day three could prove decisive.