Ireland joined Australia at the top of the World Cup leaderboard after a 68 from Rory McIlroy and Graeme McDowell in the foursomes lifted them to 13 under par.
Starting the day two behind overnight leaders Australia, the Northern Irish duo produced six birdies and two bogeys in the alternate shot format at the Mission Hills Resort on Hainan Island in China.
It moved them level with Richard Green and Brendon Jones, who posted a 70. Scotland - represented by Martin Laird and Stephen Gallacher - are one off the pace on 12 under following a 69.
"Today was good," McIlroy told reporters. "Both of us are very pleased about the score that we ended up shooting today. Anything in the 60s in the foursomes format is a very reasonable score out there.
"There is still a lot of golf to be played this week so it will be nice to get out there tomorrow again and enjoy the fourballs and be aggressive and make a few more birdies. We are very pleased with how today went and we are looking forward to the weekend."
Ireland began well, picking up three birdies over the front nine. Alternate bogeys and birdies followed from the 11th but a birdie at the 16th pulled them alongside Australia after the latter made two costly bogeys towards the end of their round.
"Alternate shot is a very difficult format. Rory really putted well today, which kept things together," added McDowell.
"I've struggled a little bit on the greens the last couple of days but I was happy the way I swung the club in general today again and Rory is playing lovely.
"We are very, very happy with that performance today, four under par in this format is a pretty good effort."
New Zealand, Spain and the United States are tied for fourth on 10 under following rounds of 68, 69 and 70 respectively, while England remain in touching distance on nine under following a 69.