Lowry’s sixth birdie of the day at the 11th gave the former Irish Open winner a share of the lead, but not for long as Jacquelin knocked in a three footer at the sixth for four birdies in a row.
He was one ahead of Lowry and De La Riva, but both Otto and Manassero missed par putts from inside five feet at the fourth.
Jacquelin added another birdie at the ninth to turn in a brilliant 31.
At 14 under he was one ahead of Lowry, who was enjoying a stunning weekend and looked poised to set a daunting clubhouse target, and David Lynn.
Having made the cut with only one shot to spare, the 24 year old Lowry signed for 67 on Saturday and moved to seven under for the day when he struck his approach to within five feet at the 14th.
Lynn had briefly led on Saturday, and a birdie at the first and 30 foot eagle on the par five fifth took him to within striking distance again.
De La Riva, Otto, Julien Quesne, Marcel Siem and Graeme Storm were all two off the pace.
Jacquelin hit a wild second to the 12th, and by failing to get up and down from the rough fell into a five-way tie with Quesne, De La Riva, South African Hennie Otto and 18 year old Matteo Manassero.
Lowry was not part of it after bogeying the long 16th and 17th. He was bunkered on both and three-putted the first of them.
A par on the last gave him a 67 and the joint clubhouse lead at 11 under, but although only two back he was in a tie for ninth.
It was Quesne who broke the deadlock from 12 feet on the 14th, and when he holed from the same range on the next The Challenge Tour graduate, 322nd in the Official World Golf Ranking, was two in front at 15 under.
Quesne made it three birdies in a row by two-putting from over 60 feet at the long 16th, then converted a seven foot chance on the last to equal the course record of 64.
It gave him a 17 under aggregate, but De La Riva's birdies at the 13th and 14th brought him two behind and so it was not over yet.