Dustin Johnson is ready to shed his 'nearly man' tag as he lurks menacingly on the shoulder of Open leader Darren Clarke heading into Sunday's final round. The big-hitting 27-year-old American was the undisputed hard-luck story of 2010, coming agonisingly close to breakthrough major victories at the US Open and US PGA Championship only to fall short. But Johnson showed great character to thrust himself into the reckoning at Royal St George's on Saturday, where a two-under-par 68 saw him finish the day on four under, just one behind Clarke. Johnson said we would learn from his near-misses last season as he planned to hunt down Clarke on Sunday. "Obviously I've been in this situation a few times, so I think the more and more you can put yourself in a situation, the more comfortable you get," Johnson said. "I'm going to be pretty comfortable out there tomorrow because I know what to expect. I know how to approach it, and I know what I do in those situations. "So I do understand it, so hopefully I can go out tomorrow and play some solid golf like I've been doing the last few days. "But it's just another round of golf. I need to keep doing what I'm doing, stay focused one shot at a time and just take what the golf course gives me." If Johnson succeeds on Sunday, few could begrudge him a victory which would represent a gutsy comeback following his travails of 2010. He had looked certain to land a first Major at the US Open at Pebble Beach last year, when rounds of 71-70-66 gave him a three-shot lead over Graeme McDowell heading into the final round. But a calamitous 82 in the final round left him tied in eighth spot while McDowell stole in to claim the title. Worse was to follow in the in the final round of the PGA Championship, where Johnson took a one-shot lead heading to the 18th the final hole. A bogey appeared to have done enough to earn him a place in a three-way play-off with Bubba Watson and Martin Kaymer. But a two-stroke penalty for grounding his club in a bunker meant he was ruled out of the play-off, eventually won by Kaymer. This week at Sandwich he has battled through a mystery virus to put himself in the reckoning on the final Sunday of a Major for the third time in little more than a year. "Still not 100 per cent, but each day has got a little bit better. Thursday I felt terrible, yesterday I felt pretty good, today I feel okay," added Johnson, who also struck a hole-in-one during Thursday's opening round.