Mediate shot his lowest score on the PGA TOUR in four years, opening the Buick Open on Thursday with an 8-under 64 for a one-stroke lead.
'This has been one of the best years of my life coming out of this injury,' he said. 'I'm ecstatic.'
Brett Quigley, Woody Austin and Brian Bateman shot 65s and Jim Furyk was among a group of four another stroke back, in a tournament up for grabs without Tiger Woods and Vijay Singh in the field for the first time since 2001. The stars have combined to win four of the previous five Buick Opens, reaching 24 under to win the previous two.
'It doesn't matter if Tiger or Vijay are here,' Austin said. 'Each of the years they won, they didn't blow the field away. I don't believe either one of them has broken Robert Wrenn's record (26 under). Somebody shoots low every year.'
Mediate likes his chances because his right hip joint is not making his back miserable anymore.
'I can move again,' he said.
Mediate credited Cindi Hilfman, a physical therapist in Los Angeles, for turning his life and career around since they connected in February.
'Since I had back surgery in '94, it's been on and off again,' he said. 'The last three years I was dead.'
Simply breathing was painful for him and walking was impossible at times.
The five-time PGA TOUR winner had only one top-10 finish last year, ending the season a career-low 206th on the money list. Mediate was ranked 176 and 114 the previous two years after finishing between 22nd and 37 from 1999-2003.
'My game didn't go away because my ability went away,' he said. 'It's because my body went bye-bye.'
Mediate wasn't the only one to dominate one of the easiest courses on the TOUR. The day after a downpour, Warwick Hills was even more vulnerable especially with temperatures in the low 70s and only moderate wind.
He missed just two greens in regulation -- despite hitting just nine of 14 fairways -- and made 27 putts in a bogey-free day.
It was his best effort since opening 2003 at the Mercedes Championship with a final-round 63.
Mediate started strong at the Buick Open after closing the Memorial with a 65 to help him finish tied for 15th in his previous tournament. He was second at the Arnold Palmer Invitational in March and tied for ninth in mid-February at the Nissan Open, when a friend introduced him to a new physical therapist.
'No one had ever unlocked (my hip) before,' he said. 'She's brilliant -- period.'
He has at least shared the lead after the first round in three previous tournaments, and hopes to hold on for the win as he did in the 1991 Doral-Ryder Open. He won the Buick Open in 2000. Austin (1995) and Furyk (2003) are also previous winners.
The absence of last year's champion made a noticeable difference in the size of the galleries. Woods isn't defending his title because he is spending time with his wife and their week-old baby.
Mediate didn't blame the fans for staying away.
'If I had a chance to watch Tiger, I'm watching him. I'm not watching me,' Mediate said.
Singh ended his five-year string of appearances at the Buick Open because of an elbow injury.
Furyk is the only player other than Woods or Singh to win at Warwick Hills since 2002 and he put himself in contention with his 34th consecutive under-par round at the tournament.
'You basically know that you have to keep firing some pretty good numbers here,' Furyk said. 'It would be nice to get an 8 or 9 under.
'Historically, someone has gotten to 20 under.'
While fans had plenty of elbow room along the ropes, a flock followed John Daly (69) as he shot his first sub-70 round in four months. He was welcomed with a roar at No. 17, a hole known for attracting one of the PGA TOUR's loudest galleries.
'I love a rowdy crowd,' Daly said.
Daly had a 7 a.m. tee time Thursday, giving him plenty of time to enjoy the rest of his day in a unique setting before beginning the second round at noon Friday.
'I'm going to Kid Rock's studio to watch him finish his album,' he said. 'It's been great staying with him this week.'