Young guns ready to fire at Match Play

California - Masters champion Jordan Spieth has warned rivals of an energy boost while defending champion Jason Day has advised he will continue to be relentless at this week's WGC-Match Play Championship.

The pair, along with world number one Rory McIlroy, headline the youth brigade who have taken over the sport and expect to prevail as 64 of the world's best golfers prepare for the lucrative event at TPC Harding Park starting on Wednesday.

While the sudden death format has been replaced by 16 four-man groups and pool play over the opening three days, there is still only one surefire way to reach the weekend's knockout phase, win or else rely on other results.

Only group winners reach Saturday's last-16 where it becomes sudden death.

Spieth refuses to be daunted about the prospect of needing to win seven matches to claim the trophy and is excited ahead of his group matches against Finland's Mikko Ilonen, American Matt Every and Englishman Lee Westwood.

Playing a busy schedule, the 21-year-old Texan claimed the Australian Open last November, won the Hero World Challenge in December and has seven top-10 finishes in 2015 from 10 starts including two wins and two runner ups.

"If anything, the last month I'd say has put more energy into me," said world number two Spieth.

One of Spieth's potential quarter-final opponents could be defending champion Day.

The 27-year-old Australian has proven ultra formidable in head-to-head play, finishing third in 2013 and winning last year with a win-at-all-costs attitude.

He claims the mind games and refusal to concede putts that have worked for him in the past will continue at Harding Park despite it rankling some opponents. He faces Americans Charley Hoffman and Zach Johnson plus South African Branden Grace.

"I really want to have a great record here and let everyone know that I am one of the best match play players in the world," said Day. "If you play me in match play, you're going to have a tough time."

Four-times major winner McIlroy, the top seed, received no favours with the draw and will face former PGA Championship winner Jason Dufner and FedExCup winners Billy Horschel and Brandt Snedeker.

"I feel like I've drawn quite a tough group, a lot of good players," said McIlroy. "I need to play well to progress, but I feel like my game is in good shape and hopefully ready to go."