The 39-year-old from Essex shot a third-round 69 to share the lead on 12 under at the Porsche European Open with DeChambeau – one shot ahead of the latter’s fellow American, US Masters champion Patrick Reed, and Matthias Schwab.
It was a late finish at the Green Eagle Golf Courses because play was suspended as lightning flashed ahead for almost three hours during mid-afternoon.
Scotland’s David Drysdale had an eventful round of mixed fortunes which concluded with a double-bogey seven on the last hole for a level-par 72.
In contrast, McEvoy’s compatriot Paul Casey finished with a flourish for a round of 69 to lie fifth – just ahead of Berwickshire’s Drysdale, Australian Scott Hend, Italy’s Renato Paratore and Frenchman Romain Wattel, all on eight under par.
David Horsey is a third Englishman in the top ten after completing his five-under round of 67 before the weather turned.
McEvoy made ground on the front nine, taking only 32 shots to edge ahead of DeChambeau – who had led the previous evening, battled back after the rain but then dropped a shot with a missed putt for par on the 16th.
His rival, a winner on the Challenge Tour just last week, held his nerve with a solid run of seven successive pars to close out his long day in encouraging fashion despite the disappointment of missing his chance of a birdie on the last, while DeChambeau then took his to level up again.
Austrian rookie Schwab had returned after the hooter sounded during a mid-afternoon downpour to draw level with McEvoy by holing the shortest of birdie putts.
He then found trouble in the water to fall back on the 11th but recovered his composure to finish his round with a birdie and ensure he remained one of the most likely challengers to McEvoy’s bid for glory this afternoon.