Phil Mickelson is unsure how he will react to the support at the US Open as he aims to sign off from golf.

Mickelson, 39 yesterday, is set to take time out from his competitive schedule following the Bethpage Black tournament, including missing next month's Open at Turnberry, in order to be with his wife Amy, 37, who will begin treatment for breast cancer on July 1.

Given the high levels of vocal support he receives from the New York crowds whenever he is in the area, particularly when the US Open was staged at Bethpage for the first time in 2002, the fan favourite's current situation is sure to be greeted with an even greater outpouring of emotion over the next few days.

The world number two, however, is uncertain how he will cope.

"I'm not sure," Mickelson said. "I'm not sure.

"I'm going to just do the best that I can. I feel like my game is ready, but you just never know. I feel like emotionally I'm better. But you just never know. So we'll play it by ear, day by day.

"It will be a fun week. I'm putting everything I have into this week, because I don't anticipate being able to play for a little while.

"And the fact that my normal support system, Amy and the kids and so forth, aren't going to make the trip this week; I'm kind of hoping to have that or feel the support to kind of help me through the week."

Having taken time off last month following his wife's diagnosis, Mickelson said the couple had been touched by the "Pink Out" during the third round of the Colonial tournament in Texas as his fellow pros, caddies, tournament officials and fans wore pink, the colour associated with the breast cancer awareness campaign.

There was, though, inevitable rustiness when he returned to action at last week's St Jude Classic in Memphis, in which he shot a final round 75 to tie for 59th place but the three-time major winner was glad he went back to work..

"Last week was important for me to play, I thought, in Memphis," he said.

"It was important for two reasons: To get back into competition and also to have a chance to see some of our friends, the fellow players' wives, caddies, tournament directors, people who have been so supportive of us.

"The people that did one of the nicest things I've ever seen for us, which was the Pink Out in Colonial. To be able to show my appreciation to those who did that. And on behalf of myself and Amy, to be able to let them know how appreciative we are.

"It was important to do that last week so that I'm able to focus more on just playing golf this week."

Of the likelihood of him missing the Open, Mickelson said: "Most likely, yeah. Most likely. I would say probably August would be the earliest (to return).

"We won't know our treatment schedule after surgery until about a week or two, until we have some other tests done. But most likely."

Mickelson said he was happy with where his golf game was as he prepares to win a US Open for the first time having been a runner-up in the event four times, including 2002.

"I've actually been hitting the ball better than I have in a long time. And possibly ever. I know it doesn't seem like it after my score at Memphis, didn't score very well.

"But I'm really excited about how things have come along, ball-striking wise. When Amy is going through tests and I'm sitting in a hospital for 10 hours, I'm thinking about - I was thinking about a lot of things. But I would take a break and think about my golf swing. I would talk to Butch (Harmon).

"Even though we didn't hit any balls, I actually got my swing to where we wanted it to be able to hit little cut shots, control my misses, and I'm very optimistic about my ball-striking this week.

"I think the key for me will be on the greens. I putted these greens very well in '02, and if I have a good putting week, I expect to be in contention on Sunday."

That, he said, would keep him in his wife's good books.

"She's left me a number of little notes, texts, cards, hints, that she would like to have a silver trophy in her hospital room. So I'm going to try to accommodate that," Mickelson said.