Sussex require a further 210 to save the follow-on after closing day two at The Oval 358 behind Surrey at 97-3.
Jon Batty resumed on 96 and sealed his second ton of 2008 before his stand of 232 with Mark Ramprakash ended.
Ramprakash, reported by the umpires after a first day clash with Murray Goodwin, holed out for 178 as six wickets fell for 57 in a total of 455.
Sussex lost two early wickets and much will again depend on Goodwin, who moved on to 49 after being dropped on five.
Batty reached three figures with a pleasant stroke through mid-wicket, but Ramprakash began to tire and and was caught at deep square-leg five minutes before lunch.
James Benning smashed his first ball for four, but having made 36 he was caught at short-leg and the collapse began.
But Surrey's bowlers then got to work, picking up the early wicket of Chris Nash, who played on in Jade Dernbach's second over.
Michael Thornely then edged an outswinger before Sussex began a brief recovery, which was then ended by Benning's direct hit from short fine-leg to run out Michael Yardy.
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