Mattan ousted Chris Lillywhite because a seven-man escape reached the city more than three minutes clear of Lillywhite and the main field.
Mattan, 1 min 30 sec in arrears overnight, finished 2 min 11 sec ahead after 103 miles from Stratford-upon-Avon. He was sixth in the finishing sprint won by Ben Luckwell, Lillywhite's team-mate, and the relief in the Banana camp was obvious.
They are down to five riders after Keith Reynolds manfully started the race despite a plastered broken left wrist suffered in a crash on Friday. He covered some 12 miles, but having climbed Edge Hill, he retired from the battle, more because of the danger of riding one handed than the agony.
His Australian team-mate Shane Sutton, riding with bruised ribs from the same tumble, summed up the team's feelings.
'Chris may be disappointed but I am happy. The pressure is off and we are better off,' Sutton said, and a glance at the overall standings proves that.
Lillywhite is second, Luckwell has risen to third, and Brian Smith is fourth, a powerful challenge with the tougher week to come in this 1,150-mile race.
Mattan is dubious about keeping the jersey. He was 16th last year, and third best of the under- 22 riders. 'My team is not so good, so I don't think it will be possible to hold on to the jersey, especially when the course gets harder,' Mattan said.
Igor Shilkin was the day's first casualty. The Kazakhstan rider's chain snapped as he contested the Edge Hill climb, and later Ireland lost Robert Power, who quit before the race reached Norton.
Matthew Postle, a stage-winner at Welwyn Garden City, crashed on to his head, and withdrew with suspected concussion. The South African, Leon Olivier, raced on after crashing when a dog slipped its owner's grasp and ran into him, wrecking his bike.
Today the event moves to Great Malvern for a 74-mile race on a deceptively tough circuit.
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