Johnstone comments on his Qatar Masters win.
Karlsson, who held at least a share of the lead for the first three rounds this week, closed with a 1-over 73 to finish in second place at 12-under. New Zealand's Elliot Boult posted a 71 to finish at 10-under, while Olivier Edmond of France and Dean Robertson of Scotland shot 73 and 75, respectively, to tie for fourth at minus nine.
Johnstone was tied for the lead with Karlsson at 12-under after both players bogeyed the 14th. Johnstone then drove through the green at the short par-4 16th and got up and down for birdie and a one-shot edge. After he saved par out of the greenside sand at 17, Johnstone rolled in a 12-foot birdie putt at the last for what would prove to be the winning margin.
Johnstone, the winner of the 1992 Volvo PGA Championship, seriously considered giving up tournament golf several months ago when he felt his inconsistent putting game was holding him back from winning.
'I said to my wife I wasn't going to play another golf tournament until I found a way to putt and it was probably a good thing,' said the 44-year-old Johnstone. 'It probably galvanized me into action and made me try a couple of radical changes. With the help of my friend Dr. Ken West and my coach, Simon Holmes, it's all come good.'
'I've played solid golf for the last three or four years and just haven't had any rewards with the putter whatsoever really,' said Johnstone, whose last victory prior to Sunday came at the 1998 Alfred Dunhill Championship. 'But I started putting well in Dubai last week and shot 63 on the third day.'
'I changed my putter at the beginning of [this] week and from the minute I started using it I felt comfortable and I only had 101 putts. That's my career best. From putting the worst in my life a month ago to putting the best in my life now is quite a radical change.'
Johnstone began the day one shot behind Karlsson and Angel Cabrera but quickly took the lead at 14-under with a 50-foot chip-in for eagle at the par-5 opening hole.
Although Johnstone's bogey at the 446-yard, par-4 5th momentarily dropped him back into a tie with Karlsson at 13-under, Karlsson bogeyed the 5th to again fall one off the pace. The Swede recovered the lost stroke with a birdie at the 9th and remained tied for the lead when he and Johnstone both dropped shots at 14.
Karlsson, who shot a course record 63 to share the first-round lead with Mark Pilkington of Wales, wasn't disappointed despite the fact he was 10 shots worse on Sunday.
'I'm happy with the way I played if you look at the week as a whole,' Karlsson said. 'Even the last round, although the score was higher I think it was a lot better than yesterday or Friday. But [Johnstone] won the tournament, I don't feel like I lost it.'
Only 13 players in the 76-man field managed to break par in Sunday's swirling winds, with Johnstone and Boult as the only top-10 players from the third round to record sub-par scores over the final 18 holes.
Argentina's Cabrera followed up his third-round 67 with a 6-over 78 on Sunday to finish with John Senden of Australia at minus seven.
Defending champion Rolf Muntz tied for 13th at 5-under, while Thomas Bjorn, last week's winner in Dubai, tied for 23rd at minus three.
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