Defending champions Patrick Cantlay and Xander Schauffele made the biggest move of the day, rocketing up the leaderboard with a nine-under 63 – the best score of the round by three strokes.

They ended at a 14-under through 36 holes, leaving them tied for fourth two shots behind Clark and Hossler.

Hossler made a birdie putt of nearly 60 feet on the par-4 4th hole to highlight his team's bogey-free round on Friday.

"It was a fairly stress-free round," he said.

"With the exception of the long putt on 4, we didn't do anything crazy. We also didn't really make any mistakes. It was a really clean round."

Three of the five birdies by Clark and Hossler came on par-5s after they either hit or narrowly missed the green in two. Their final birdie came shortly after a two-hour, 28-minute delay caused by rain and lightning.

"We needed to be aggressive here in alternate shot, which is a little dangerous." - Xander Schauffele.

"We're in a great spot," Hossler said. "I like our mentality."

Cantlay and Schauffele looked more dialled in than during their erratic fiive-under first round on Thursday that was marred by three bogeys in better-ball play.

They opened the more challenging alternate-shot second round on the 10th hole and birdied four of their first seven.

They eagled the par-5 18th, set up by Schauffele's towering, 264-yard hybrid that settled less than 15 feet from the hole.

Cantlay drained the putt, giving the pair a six-under 30 at the turn – a tournament record for nine holes in alternate shot.

"We needed to be aggressive here in alternate shot, which is a little dangerous," Schauffele said.

The teams of Sam Ryder-Doc Redman, and Sungjae Im-Keith Mitchell, ended the day tied for second at 15-under.

Sean O'Hair and Brandon Matthews, who began the day tied for first, slipped back into a tie for fourth after a round-two 69.

None of the five Australians involved in the Zurich Classic made the cut.

Greg Chalmers and Cameron Percy hit a second-round 69 to finish at seven-under after 36 holes, while Aaron Baddeley and Harrison Endycott were five shots further back.

Geoff Ogilvy, paired with US golfer Kevin Stadler, carded 72 for an overall four-under.

The cut was at 10-under, meaning all 35 remaining teams slated to play in Saturday's better-ball third round were within six shots of each other.

The final round is alternate shot.