(Reuters) - Reigning champion Dustin Johnson is favorite to win a fifth World Golf Championship (WGC) title this week in Mexico City where the world number one will stare down a strong field featuring six of the world’s top 10 golfers.

FILE PHOTO - Feb 18, 2018; Pacific Palisades, CA, USA; Dustin Johnson plays his shot from the second tee during the final round of the Genesis Open golf tournament at Riviera Country Club. Mandatory Credit: Orlando Ramirez-USA TODAY Sports

Johnson’s victory last year came during a red-hot stretch in which he won three consecutive tournaments, including the WGC-Match Play event, before his run was halted by a freak back injury on the eve of the U.S. Masters.

The long-hitting American already has three top-10 finishes in four PGA Tour starts this season, including a January victory at Kapalua, and will tee off at Club de Golf Chapultepec with an eye on gaining some momentum ahead of the April 5-8 Masters.

Johnson, 33, has enjoyed plenty of success at WGC events and first won this tournament in 2015, when it was held at Trump National Doral in Miami. His victory here last year earned him the world’s number one ranking.

But for him to defend his title, he will have to fight off every top 50 player except for Jason Day, Hideki Matsuyama, Rory McIlroy, Henrik Stenson, and Brooks Koepka, making it as deep a field as one will find ahead of the Masters.

Among the other top players in the field this week are world number two Jon Rahm, who finished third here a year ago, and reigning Player of the Year Justin Thomas, fresh from his Sunday triumph at the Honda Open and showing no signs of slowing down.

Johnson, Rahm and Thomas, who have been grouped together for the opening two rounds, will tee off on Thursday from the 10th tee at 12:51 ET (1751 GMT).

Phil Mickelson, who won the event in 2009, will tee off with plenty of confidence as he has earned top-10 finishes in each of his last three starts, including a share of second place at the AT&T Pebble Beach Pro-Am.

World number five and former champion Justin Rose, who won the WGC-HSBC Champions event in Shanghai last October, returns to action after a four-week break.

The Englishman, who came within a whisker of winning the U.S. Masters last April where he fell in a playoff to Sergio Garcia, edged Johnson in Shanghai and is vying to become only the third man in history to claim back-to-back WGC titles.

Last year’s runner-up, Briton Tommy Fleetwood, is coming off a fourth-place finish at the Honda Classic and will be eager to return and seek his first PGA Tour win.

Fleetwood has been grouped with Masters champion Sergio Garcia of Spain and Swede Alex Noren.