Sussex needed to get their sums right as they pressed for a first Championship win of the season at Hove this weekend.

They closed the third day against Nottinghamshire on 237-5, a lead of 309 and the balancing act this morning will be deciding when they have enough runs on the board to insure against defeat while leaving themselves enough overs to bowl out their opponents on what is still an excellent batting track.

Coach Peter Moores said: "I think if we have 80 overs at them that could be long enough to bowl them out.

"If we play like we did yesterday we will give ourselves a good chance. I thought we did really well, our bowlers took the game by the scruff of the neck and then we batted really positively."

After Jason Lewry had claimed his second successive five-for against Nottinghamshire, Sussex, with a lead of 72, rattled along at over four runs an over once they had seen off South African Greg Smith who was head and shoulders above the rest of the visitors' attack.

Richard Montgomerie played himself back into form with 66, but the day's best batting came from Michael Yardy who made a maiden first-class 50 a week after achieving that landmark for the first time in one-day cricket.

Yardy is another of the young players, along with Bas Zuiderent and Matt Prior, to have grabbed his opportunity with both hands in the early weeks of the season.

Seasoned Sussex watchers must have found it hard while he was blazing the ball to all parts yesterday that this was the same player who made such a nervy debut when he was thrust into the side at the end of last season.

Yardy worked hard in the winter on his fitness and, a stone lighter, he is now starting to look the part. Confident and aggressive from the first ball, the quality of his off side play in particular had a crowd basking under a cloudless sky purring with delight.

Sussex lost Murray Goodwin in the third over when Smith found extra bounce at the sea end to defeat a rather leaden-footed swish outside off stump by the Zimbabwean.

In two spells Smith bowled outstandingly and it was a pity for Nottinghamshire's sake that none of his team-mates took a lead from the stocky South African.

Paul Franks cannot have made much impression with England's chairman of selectors because David Graveney was nosing his car out of the Tate gates at about the same time Franks, who played in last summer's one-day series, was being withdrawn from the attack after a new ball spell of just three wayward overs.

With Gareth Clough injured and out of the attack, Nottinghamshire were soon whistling up their second string bowlers and Yardy took full advantage, most memorably when he square drove Greg Blewett to the boundary between two fielders either side of point who were standing no more than five yards apart.

His half century came off 66 balls with eight fours and he had added two more boundaries when Blewett, who had a very good lbw shout turned down the ball before, found the edge and wicketkeeper Chris Read, whose busy display will have impressed Graveney, took another good catch diving low to his left.

The pair had put on 128 in 28 overs and Montgomerie maintained the momentum, pulling Usman Afzaal emphatically to the mid-wicket fence to reach his first half-century of the season.

Smith returned for another blast down the hill after tea and suddenly it looked a different game again. Montgomerie had moved on to 66 when Smith snared him with an absolute beauty which bounced and left him before taking the edge.

Sussex lost their way a little after that with three middle order wickets falling in five overs. Will House, neither forward nor back, had his off stump trimmed by a good length delivery from Smith before Zuiderent was bowled by Afzaal after getting a bottom edge to an attempted sweep.

Smith has proved there is something in the pitch for bowlers who bend their backs. Not that Sussex's attack will need too much encouraging after taking the last six wickets for 118 in more or less one session as Nottinghamshire were bowled out for 332 and Sussex claimed a full hand of bowling bonus points.

Lewry castled Paul Johnson with an cracking inswinger in his third over before returning for a second spell either side of lunch to wrap up the innings.