With winds kicking up -- and making low scores difficult -- Rock had one of the rounds of the day with an eagle and four birdies. Uihlein had a bogey and five birdies in his second round for a 68.
The leaders are at 9-under 135 after 36 holes.
Ricardo Santos also shot a second-round 66 and is in a five-way tie for third at 7-under. Jose Maria Olazabal, with a 69 Friday, Shane Lowry (70) Joost Luiten (70) and first-round leader Oscar Floren (71) are also at 9-under.
Pablo Larrazabal and Raphael Jacquelin, who both had second-round 69s, are tied for eighth at 6-under.
Rock, playing the second nine of the Carton House Golf Club first Friday, opened with a birdie at the 10th hole and added back-to-back birdies at Nos. 13 and 14. He added a birdie at the first before posting eagle 3 at the par-5, 605-yard fourth hole.
Uihlein also opened Friday with a birdie at the 10th hole and made the turn at 3-under after birdies at 13 and 15. He dropped in another birdie at No. 1 but slipped back with a bogey at 3. A birdie at the fifth hole put him in front.