The 2013 winner trails American Gary Woodland by a shot in the season’s third major, with Rose relishing his chance to repeat a success in the USGA event at Merion.
“I’m in a great position going into [Sunday],” said the Englishman after closing the third round with a birdie for a 68 and a 10-under-par 203 total.
“Had a great day with Gary. He’s awesome to play with. For both of us, we are good friends. From that point of view, it’s going to be a fun day.
“One back gives me the freedom to feel like I’ve got everything to gain, nothing to lose. I’m close enough that I have to build my plan, build my round of golf, be disciplined.”
Woodland, the halfway leader, has never won a major nor played in the final group on Sunday.
The three-time PGA Tour winner escaped a few potential disastrous holes on the back nine in the third round to post a 69 for a 202 total.
He holed a 33-foot chip for par on the par-3 12th and a 42-foot putt for par on the par-5 14th.
“I feel very comfortable on this golf course,” said Woodland, who tied for sixth in last year’s US PGA Championship.
“I’ve been a cutter of the golf ball a long time. [Instructor] Pete Cowen has got me comfortable working the ball both ways if I need to. And that just frees me up a little bit.
“I also have a short game now I can rely on. I don’t have to focus on the ball-striking.
“It’s nice to be where I’m at right now and I’m looking forward to going out and doing it one more day.”
Seven major champions sit within seven strokes of the lead, including double defending champion Brooks Koepka, who sits on seven-under.
“Just keep doing what I’m doing,” said Koepka after carding a 68. “Obviously, whatever I’m doing is working. Make a couple of birdies [on Sunday], put some pressure on guys.”
Also lurking four shots behind are 2010 Open champion Louis Oosthuizen and American Chez Reavie, with 2011 champion Rory McIlroy a further shot back.
Three more major winners – Graeme McDowell (2010 US Open at Pebble Beach), Danny Willett (2016 Masters) and Henrik Stenson (2016 Open Championship) – are seven back on four-under.
Masters champion Tiger Woods, who won by 15 shots at this venue in 2000, sits 11 off the lead after an up-and-down 71.
American Brandon Wu is the leading amateur on two-under, two shots ahead of Norwegian Viktor Hovland.