Phil Mickelson, bottle of energy drink in hand, held on to win the WGC-CA Championship at Doral on Sunday after receiving medical treatment for dehydration.

Mickelson was put on a drip at a local clinic three hours after finishing his round on Saturday when he was struggling for energy and fluids.

"I was shaking for an hour, I had the cold sweats. I took a hot shower and that didn't do it, a hot bath and I almost burned myself trying to get warmed up. That's when I decided to go [to the clinic]".

After keeping fellow-American Nick Watney at bay to win with a 19-under overall on Sunday, Mickelson said he had been suffering from a virus throughout the tournament.

"I just haven't eaten in three days, So I'm weak. That's why I've been so slow walking the last few days, I was 50 yards behind everybody," he said.

"I just had a problem keeping food down or fluids in, so I may stay over one more night just get an IV bag or I may try to get home and get in bed, I'm not sure."

Mickelson said there was never any doubt over his participation on Sunday even though he was in bed until nearly an hour before his start time.

"They say beware of the ailing golfer. I knew going in I was going to play well.

"I was in bed until 1.30pm and didn't have the energy today. I just worried about my own shot, tried to maintain an even pace and made sure I was drinking fluids.

"I got half a sandwich down today and a banana which is the best I've done."

Although the win was Mickelson's first at a World Golf Championship event he said he was most pleased by the fact he heads into the build-up to next month's Masters in such good form.

"It feels great because I'm starting my Masters run to Augusta, this all part of the process," he said.

Watney was inches away from a birdie that would have taken the match to a play-off and Mickelson said he felt for his rival.

"As Nick's ball rolled up to the hole it looked like it was going to go in -- I've been there man, I know that feeling and it is not a great one.

"I'm fortunate to be able to come out on top," he said.