The Argentine was at 11-under 202 after starting the day with a two-stroke lead on Kaymer.
Just a little nervous today, said Echenique, who is seeking his first victory on the European Tour. On No. 1, I missed a putt from 1 or 2 feet. I was not relaxed on the first three holes. But after that, I made long putts on the No. 4 and the No. 5.
Paul Waring of England had a 68 to climb from seventh to third, two strokes off the lead and one better than compatriot Seve Benson, who also shot a 68.
Benson had a share of fourth with Richard Green of Australia (70) and Peter Hanson of Sweden (70).
Englands Lee Westwood (70) and Ian Poulter (66), four and five strokes back respectively, also remained in contention.
I didnt miss a fairway, I didnt miss a green so it was pretty flawless, said Poulter, a runner-up at the British Open last year. Apart from the second shot into the last (hole), which I thought was pathetic, I was already thinking about my lunch. It was pretty clinical.
Echenique was briefly caught by the chasing pack after the turn when he fell into a tie for the lead with Waring and Charl Schwartzel of South Africa at 10 under.
A runner-up at the BMW International Open in Munich last weekend, Echenique started his third round slowly with a bogey on the first hole.
Waring, ranked No. 130 on the European Tour, hit an approach from the rough that landed a few feet from the pin on No. 6 and helped him tie Echenique atop the leaderboard at 9 under.
But Echenique regained a two-stroke lead by sinking two straight birdies, including a 20-foot putt on the fourth.
Another bogey from Echenique on the eighth again cut his lead, allowing Schwartzel to pull even at 10 under with two consecutive birdies.
Waring picked up a shot on the 13th to join them, but he slipped back to third with a bogey on 14th, the longest hole on the Golf National course.
Schwartzels run was marred by three bogeys in four holes, dropping the South African to a share of seventh and leaving Echenique in charge.
Kaymer dropped a shot on his first hole, but played solidly the rest of the way. The European Tours 2007 rookie of the year sank two straight birdies ' after an approach on the sixth that stopped one foot from the cup and a 13-foot putt on No. 7.
There were a lot of very difficult pins today, Kaymer said. I played very safe. It was pretty much my strategy for today and its going to be the same for tomorrow.