A fortnight ago, Chris Nash had been consigned to the Sussex Second XI in a desperate search for form and, if not for a late injury to Michael Yardy, would not have played in this game. Now, in his 70th first-class innings for his county, Loughborough UCCE and British Universities, he at last reached the nineties for the first time in his career and, dancing out to drive Francois du Plessis for four, could ecstatically celebrate a hard-fought maiden century.

The value of the 25-year-old opener's resolve, and of his 125-run fourth-wicket stand with Matt Prior, who bounded to 73 in 98 balls, shone through when both men fell in six balls from Steven Croft in the 15 minutes before tea. Four more then came and went in 18 overs until a last-wicket stand swelled the lead by 40 runs to a potentially decisive 110.

Three elements were crucial. Prior, in marvellous touch all summer, so assaulted Gary Keedy on a turning pitch that, as 101 runs came in a breathless 19-over period, the spinner was smashed out of the attack with 32 conceded from his last four overs. An appalling oversight by Luke Sutton, the wicketkeeper, however, had reprieved Prior on 21 when, with both batsmen stranded in mid-pitch, Sutton failed to get to the stumps in time to receive cover point's throw.

And, as Robin Martin-Jenkins threw the bat the moment he was joined by Jason Lewry, a natural No11, Glen Chapple misjudged a testing catch in the deep that should have seen the final partnership ended a run after it began. From modest advantages, Sussex twice grew towards a potentially match-winning lead.

This was emphasised in the five overs left before the close when Martin-Jenkins, rubbing salt into the wound, moved one away to have Lou Vincent smartly held at slip. Keedy, the nightwatchman, has something to repay with the bat today for, though he finally struck in his seventeenth over to become the 30th Lancashire bowler to take 500 wickets, the crucial afternoon phase had long since been lost.

It has been a season of limited rewards for Keedy but the fault was hardly his alone. Dominic Cork, on his 37th birthday, and Chapple took three wickets between them but neither sustained real menace and Sajid Mahmood was woefully erratic.

In an innings in which Martin Jenkins's unbeaten 27 was the third-best score, the inability to dislodge Nash, who finally fell for 108 from 204 balls, and nip Prior in the bud may well have cost the game.

Scoreboard

Lancashire: First Innings 206 (O P Rayner 5 for 65)

Second Innings
L Vincent c Rayner b Martin-Jenkins 4
P J Horton not out 5
G Keedy not out 0

Total (1 wkt, 5 overs) 9

Fall of wicket: 1-9.

Bowling: Lewry 3-1-7-0; Martin-Jenkins 2-1-2-1.

Sussex: First Innings (overnight 9-0)
C D Nash lbw b Croft 108
M A Thornely b Cork 5
L J Wright c Sutton b Mahmood 20
M W Goodwin c Sutton b Chapple 18
M J Prior c du Plessis b Croft 73
*C J Adams lbw b Keedy 18
C D Hopkinson run out 9
R S C Martin-Jenkins not out 27
O P Rayner c Chapple b Keedy 0
Mushtaq Ahmed c Croft b Du Plessis 7
J D Lewry b Cork 15
Extras (lb 8, nb 8) 16

Total (95.3 overs) 316

Fall of wickets: 1-18, 2-71, 3-108, 4-233, 5-238, 6-266, 7-267, 8-269, 9-276.

Bowling: Chapple 12-4-26-1; Cork 15.3-4-37-2; Mahmood 14-1-80-1; Croft 14-3-38-2; Keedy 22-4-74-2; Du Plessis 18-2-53-1.

Umpires: J H Evans and T E Jesty.