Local favorite Ian Woosnam was one shot further back at 5-under-par 64 along with Stuart Little.
Jimenez started on the 10th tee of the Roman Road Course at Celtic Manor Resort and picked up his first birdie of the day at the par-3 11th. Jimenez then drained a 14-foot putt for a birdie at the par-5 16th and followed that up with a birdie at the 17th to make the turn at 3 under.
Lynn also played the back side first and bogeyed the 10th. He responded with four birdies over his next five holes and hit his tee shot inside 7 feet for a birdie at the par-3 second. Lynn converted a 6-foot putt for a birdie at the following hole to get to 5 under, but he found trouble with a bogey at the fourth.
The Englishman dropped his approach within 12 feet for a birdie at the par-4 seventh and made it two in a row with a birdie at the par-3 eighth.
'It's just one of those days,' said Lynn, who birdied all five of the par-3s on Thursday. 'I hit them all pretty close.'
Emerson bogeyed the opening hole, but he countered with three birdies on the front nine. He made a move with three consecutive birdies starting at the par-3 11th and reached 6 under with a birdie at the 16th.
He stumbled to a bogey at the very next hole, but hit his second shot to 6 feet for a birdie at the par-4 18th.
Heath also bogeyed the first, but recovered with back-to-back birdies from the fourth. The young Englishman added a birdie at the eighth and ran off four birdies on the back nine for his 63.
'The difficulty around this course is the greens,' said Heath. 'You can't go at all of them, but you've just got to play aggressively when you can and then stay patient when you can't.'
Senior got to 6 under with a birdie at the 13th, but he suffered a double bogey at the very next hole that dropped him back to minus-4. Senior recovered with back-to-back birdies from the 16th for his share of first.
Teilleria had three birdies over his last six holes for his 63.
Nick Dougherty posted a 4-under-par 65 to finish two shots back alongside Michael Campbell, Kenneth Ferrie, Andrew Coltart, Jose-Filipe Lima, Neil Cheetham, Jean-Francois Lucquin and Alessandro Tadini.
Defending champion Simon Khan managed four birdies and two bogeys to finish in a group at 2-under-par 67.