BEN BROWN admits Sussex must develop a killer instinct after their promotion bid suffered a massive setback.

The county went down by 45 runs at home to Derbyshire after losing seven wickets in the final session yesterday.

They were set a daunting 390 for victory but looked like pulling it off going into the evening session.

Now they require wins at Durham and home to Nottinghamshire as the Specsavers County Championship season reaches its finale.

Brown fears his side may be becoming nearly men.

He said: “In terms of winning key moments, you have to look at the season and say we haven’t done that in general, both with bat and ball.

“We have fallen short in the three competitions and we have to look at the reasons why.

“Whether we are losing key moments in key matches, for what reason we are losing them, we have had had a pretty honest chat in the dressing room of how we have got to go forward and get better, areas to address.

“There has to be some reason why we are not getting over the line in all three formats.”

Brown defended his decision to put Derbyshire in but admitted Sussex were not good enough for two days. “We are hugely disappointed.

“I thought we bowled and batted poorly in the first innings and you can’t always claw it back.”