Heat will be a major factor at this week's US PGA Championship at Southern Hills, according to Masters champion Zach Johnson.

Temperatures are expected to peak at around 101 degrees (38 degrees Celsius) for the rest of the week at Southern Hills Country Club. Johnson plans to conserve as much energy as he can before Thursday's opening round.

"Dealing with the heat is going to be of the utmost importance," American Johnson said.

"I'm not going to wear myself out Monday through Wednesday. That's first and foremost. I'll play nine holes today and play as much as I can off the golf course.

"I don't want to be out there whacking balls for two hours. I'll be more focused on just getting some of the fundamentals down and then getting the speed of the greens."

Organisers have issued an excessive heat warning for the week and the heat index, which combines air temperature and relative humidity, is expected to reach 110 for the first two rounds.

"It's going to be really hot every day, so it's going to be not only a test of golf but also a physical test and a mental test," Johnson added.

The 31-year-old from Iowa, who held off a late challenge by Tiger Woods to claim his first major title by two shots at the Masters, is happy with his form going into the final major of the year.

A twice winner on the 2007 PGA Tour, Johnson tied for 11th at the WGC-Bridgestone Invitational after shooting a joint best-of-week 65 in the second round.

"I feel like my game is at a good point to come and play and compete this week," he said.

"I like this course because it's not terribly long," Johnson added, referring to the 7,131-yard, par-70 layout. "You don't have to overpower it, which is good for me.

"With all the elements - being a major, with the heat and just the golf itself - it's going to require mental discipline and some pretty unbelievable courage to keep focused."

Regardless of how well he plays this week, the American is especially looking forward to his introduction as 'Masters champion Zach Johnson' in the opening round.

"It's flattering," he said. "The first time it was announced was at Hilton Head [the week after the Masters] and I got goose-bumps. It was pretty neat and it remains very, very cool.

"Just to be in that fraternity and have that title at least for this year is very, very special."

Johnson is scheduled to tee off from the par-four first with U.S. Open champion Angel Cabrera and Open winner Padraig Harrington at 18:10 GMT in Thursday's opening round.

Reuters