Sussex supporters have waited all season for a telling contribution with the bat from Chris Adams and it was no surprise that he produced it in their most important game for years.

No one relishes the big occasions more than the Sussex captain so it was fitting that he chose the summit meeting between the first division's top two to score his first Championship century since May 2002.

Richard Montgomerie (90), Murray Goodwin (74) and Tim Ambrose (43) gave him excellent support and not even a rare failure by Tony Cottey could prevent Sussex from taking control against Surrey.

They resume today on 362-4 and, if their first day performance has set the tone for the remainder of the match, there is every chance that Sussex could swap places with their old rivals some time on Saturday.

Only then, perhaps, will Adams and his team-mates finally be convinced that they are capable of winning the Championship for the first time in the county's long history.

The captain reiterated his belief that Surrey are still favourites to land a fourth title in five years on national radio on Tuesday night, but a few hours later his side were offering compelling evidence to the contrary. The very least Sussex supporters will expect now is that, injuries permitting, they sustain their challenge until the very last few days of the season.

After winning the toss and taking first use of an easy-paced pitch, Sussex batted with all the confidence of a side who have won four out of their last five Championship games and who fear no one at present, not even a side boasting ten full internationals.

Goodwin and Montgomerie built the platform by scoring at five runs an over in the morning session as they posted their first century partnership of the season.

Adams and Montgomerie had to rebuild when Goodwin and Cottey fell in successive overs just after lunch. Their third wicket stand of 88 spanned 31 overs and reflected just how much better Surrey bowled in the afternoon.

But after Montgomerie had fallen to Ian Salisbury just before tea, Adams and the increasingly authoritative Ambrose took the attack to Surrey once again.

The captain desperately wanted to make a telling contribution to Sussex's success and a couple of weeks ago set himself the target of scoring three hundreds in the last seven games.

If he achieves it he will undoubtedly reflect on a 'back to basics' net session with director of cricket Peter Moores after he had been dismissed for a first innings duck at Grace Road a fortnight ago as the turning point in his season.

He was back to something approaching his best at Trent Bridge last weekend and yesterday it was hard to recall a false stroke. He played and missed a couple of times at Saqlain, distracted perhaps by the white bandanna the Pakistani twirler wore as he sent down 36 overs unchanged at the sea end after coming on in the over before lunch.

But it was Adams of old as he punched drives through the off side, pulled anything short with power and authority or used his feet to pick off singles against the spinners.

He helped Sussex re-assert their control after tea by sharing a fourth wicket stand of 98 in 26 overs with Ambrose who showed no ill effects of the knee injury which sidelined him for a week. Dropped at slip on 33, Ambrose fell after adding ten more when he pushed forward to Salisbury.

By then Adams was in the nineties and as he closed in on his 13th century for the county every run was applauded by a crowd almost as nervous as he was. A push into the covers off Saqlain got him to the landmark and his delight at getting there was only too apparent as he acknowledged the standing ovation with a grin almost as wide as his bat.

A few moments later Sussex had narrowed the gap at the top to just two points when they went past 350. For the county and their captain the day could not have gone any better.

The tone had been set early by Montgomerie and Goodwin, both of whom played like men who have rediscovered their best form at just the right time of the summer.

Goodwin had sated his appetite for big runs with 148 against Nottinghamshire on Saturday and he gorged himself again yesterday as James Ormond and Martin Bicknell wasted the new ball by offering Goodwin the width to play his favourite shots through the off side.

His 114-ball innings included 12 boundaries and it was a surprise when he played down the wrong line to Ormond in the first over after lunch and lost his off stump. The 149 they put on was Sussex's biggest first wicket stand for nearly 14 months.

When Cottey played back to Saqlain Mushtaq's quicker ball in the next over most of the 1,500 crowd would have been forgiven for thinking that this was the signal for the champions to start imposing themselves.

Montgomerie certainly lacked his earlier fluency but the bowling was a lot more accurate. He added 23 runs in 33 overs in the afternoon and after just over four hours at the crease lost his off stump to Salisbury's leg break. He hit 13 boundaries and faced 201 deliveries.

But by then Adams was starting to impose himself and if Sussex can go on to post a total in excess of 450 today the stage will no doubt be set for Mushtaq Ahmed. The Surrey spinners bowled 50 overs between them yesterday, a workload Sussex's leg spinning magician would relish on his own on a pitch which will give the twirlers increasing assistance.