County Championship D1, Hove: Sussex 362-4 v Surrey
Sussex captain Chris Adams bounced back to form in the most critical match of the season to date to hit a century against top-of-the-table Surrey.
The champions began the day with a five-point lead over Sussex.
But after the first day, Sussex had reduced the deficit to just two as the home team reached a tremendous score.
After the home team won an important toss, Sussex lost just four wickets all day.
Richard Montgomerie reached 90, finally falling to Ian Salisbury, but Adams (107 not out) Murray Goodwin (75) and Tim Ambrose (43) were also in the runs.
Both teams had included two specialist spinners on a track which currently looks ideal for batting but which could turn later.
But Saqlain Mushtaq has so far sent down 36 overs to claim just one wicket.
Sussex: R R Montgomerie, M W Goodwin, P A Cottey, C J Adams (Capt), T R Ambrose (Wkt), R S C Martin-Jenkins, M J Prior, M J G Davis, Mushtaq Ahmed, R J Kirtley, P M Hutchison.
Surrey: I J Ward, J N Batty (Wkt), M R Ramprakash, G P Thorpe, R Clarke, A J Hollioake (Capt), Azhar Mahmood, M P Bicknell, I D K Salisbury, Saqlain Mushtaq, J Ormond.