Rory McIlroy World ranking: No. 6 | Scores: 71-68The former No. 1 in the world had a solid 2-under 68 on Friday. He sits 9 back of Kaymer heading into the weekend with a 1-under total. Last year at Merion, McIlroy struggled on the weekend with rounds of 75 and 76 to finish in a tie for 45th.
Jason Day World ranking: No. 7 | Scores: 73-68On Friday, the two-time U.S. Open runner-up had a 2-under 68 to get to 1-over for the championship. He's way off the lead, but a couple more 68s might nab him a top-10.
Sergio Garcia World ranking: No. 8 | Scores: 73-71A double-bogey at the par-4 11th hole was the major blemish on the Spaniard's round. All he did on Friday was play well enough to make the cut with a 1-over 71 for a 4-over total.
Justin Rose World ranking: No. 9 | Scores: 72-69In his second round, the reigning U.S. Open champion had only two bogeys -- a significant improvement over his five on Thursday -- for a second-round, 1-under 69. Curtis Strange's record of back-to-back U.S. Opens in 1988 and '89 looks very safe.
Jordan Spieth World ranking: No. 10 | Scores: 69-70