Mickelson fired a five-under-par 67, boosted by an extraordinary eagle-eagle-birdie stretch on the back nine, and Couples carded a 68 on Saturday to get back into contention heading into the final round.
"It was pretty funny because we were texting a little bit about how low I was going to have to go to catch him and maybe play with him tomorrow," 50-year-old Couples, the 1992 winner, told reporters.
"For a time there, we were both playing pretty well, but then he went eagle, eagle, birdie, and that's a pretty big jump to get going, and I chipped it on 15," he said about his own eagle-three on the par-five hole.
After Mickelson holed out from the fairway at the par-four 14th for his second successive eagle, Couples was seen shouting to the big left-hander."I wanted that golf ball that he holed in at 14. That's what I wanted," said Couples, who played in the group ahead of Mickelson. "He couldn't hear me, but I wanted that eagle ball.
"And then I chipped in on the next, so I told him he could have my eagle ball. That was pretty neat."
Mickelson finished the day one shot behind leader Lee Westwood of Britain. Couples was five strokes off the pace.Couples was a surprise first-round leader after an opening 66 before his bad back acted up as he soared to 75 on Friday.
The smooth-swinging American said his back felt all right in the third round, but he found it tiring to tour the hilly Augusta National layout."I feel like 100 standing here to be honest with you, but I don't feel 50 playing golf."
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