Skipper Chris Adams today warned that Sussex's promotion challenge could be over if they lose another game.

The county lost their first Championship game for three months, going down by an innings and 17 runs to leaders Northamptonshire on Saturday.

Defeat means they have slipped down to fourth place in Division Two with four games to go, the first of them on Wednesday when they play the return fixture against Northants at Eastbourne.

Away games against Glamorgan and Nottinghamshire follow before Sussex entertain Gloucestershire at Hove when, Adams predicts his side will at least need to get some bonus points to make sure of a place in the first division next season.

Wins for Essex, who have now gone second, and Middlesex have simply made a tight league even more congested.

Essex, who are second, have a 15 point lead over Sussex, but third placed Worcestershire and Middlesex, who are next to bottom, are separated by just ten points and both Glamorgan and Warwickshire have a game in hand.

"I don't think we can afford to lose another game," said Adams. "It's so tight that if you do you can lose a lot of ground which is going to be hard to make up as your matches run out.

"Two wins should be enough to get you promoted, but I definitely think we will have to get some points from the final match to stay in the top three."

The meeting with Gloucestershire is still a month away of course. Adams' immediate concern is to raise morale for the return fixture against a Northamptonshire side brimming with confidence after winning four of their last five games to go from seventh to top.

And the captain has hinted that there will be changes to the team. Seamers have traditionally done well at the Saffrons in recent years and Sussex's proud record of wins in their last four matches there is one they intend to maintain.

Mark Robinson seems certain to be recalled, probably at the expense of Justin Bates who made little impression on a spin-friendly Northampton pitch and who could struggle to make any impact at Eastbourne where recent county wickets have offered just gentle turn.

Sussex's much vaunted 'awesome foursome' seam attack have played together just once since the end of May because of injury and non-selection and Adams seems keen to reunite them as the season reaches a crucial stage.

"I've always said that without Robbo we're not quite the same and I think we need to get him back in the side. He'll be quite fresh which is another bonus at an important stage of the season," added Adams.

There may also be a change in the batting with opener Toby Peirce's place most under threat. The left-hander has consistently got starts this season, but he has made just two half-centuries - the last ten weeks ago - and his average has dipped below 20 after two disappointing scores against Northamptonshire.

Wasim Khan will probably revert to his favourite position as opener which could leave a slot open in the middle order for either Will House or Bas Zuiderent, both of whom came close to selection for the Northants game after making their highest scores for the county in the National League win over Lancashire last Monday.

Adams is confident that Sussex can turn the tables on Northants on home soil, although it will be interesting to see if the visitors' off-spinners, Graeme Swann and Jason Brown, have the same mesmeric effect on Sussex's batsman which they enjoyed on home soil.

Brown finished with match figures of 9-152, recording a career-best 7-78 to wrap up the Sussex innings after just 20 balls resistance from their last wicket pair on Saturday.

Fifteen of the Sussex wickets in the match fell to Brown and Swann and only Tony Cottey resisted them, adding another eight on Saturday to his overnight 104 before he played on to become Brown's 50th wicket of the season, 46 of which have been taken in the last five games.

Cottey's 112 came off 145 balls with 12 fours and two sixes and his performance, along with those of Khan, Umer Rashid and James Kirtley, were the only crumbs of consolation Adams could find amid the desolation of a comprehensive defeat.

"It's obviously disappointing but I'm not too downhearted," he said. "We've bounced back before and we can do it again, that's the nature of this team.

They are a hardworking side who desperately want something to show for their efforts at the end of the season and I think they will."

SCORES: Northants 460 (Warren 151, Penberthy 96, Rashid 5-103), Sussex 232 (Khan 74, Brown 4-53) and 211 (Cottey 112, Brown 7-78). Northants (19pts) beat Sussex (3) by an innings and 17 runs.