World No. 1 Rory McIlroy and 14-time major champion Tiger Woods lead the qualifiers announced on Monday for next week's World Golf Championships Match Play Championship.
The top 64 in Monday's world golf rankings were set for the showdown near Tucson but exact brackets will not be established until Sunday, in part because players have until Friday to commit to play in the $8.75 million event.
Three-time Masters champion Phil Mickelson, ranked 10th, has said he will not play in the event, allowing 65th-ranked Shane Lowry of Ireland to advance into the field and make his first career start in the 64-player event.
If that position holds, Lowry would open against Northern Ireland's McIlroy, last year's PGA Championship winner.
McIlroy, Woods, England's Luke Donald and American Brandt Snedeker, who won last week's title at Pebble Beach and last year's US PGA playoff crown, would be top seeds if their ranking position holds.
Defending champion Hunter Mahan, ranked 26th, will also be in the field for the event, which begins next Wednesday with 32 first-round matches at Dove Mountain.
South Africa's Richard Sterne made a major jump Sunday to book a berth in the field, leaping from 94th to 55th in the rankings by virtue of his victory at the Joburg Open.
Six other players moved from outside the top 64 at the start of the year to crack the lineup for the WGC Match Play, including Thailand's Thongchai Jaidee, who was 80th to open the year and now ranks 54th.
The group also includes South African Tim Clark, Scotsman Stephen Gallacher, England's Chris Wood and Americans Charles Howell and Russell Henley.
Lowry edged Sweden's Fredrik Jacobson for the last spot in the lineup when Patrick Reed sank a 12-foot birdie putt on the 18th hole at Pebble Beach to share seventh with Jacobson and prevent the Swede from being ranked 65th.
At 66, Jacobson is first alternate at this stage ahead of No. 67 Bernd Wiesberger of Austria and Dane Anders Hansen.