Youngster Luke Wells struck an unbeaten 108 to help Sussex to within 147 runs of Surrey's first innings total of 351 on day two of their LV= County Championship clash at The Oval.
The son of former Sussex and Kent batsman, Alan, showed tremendous composure to reach his sixth century of his first-class career from 234 balls and with 11 fours and six.
It was the 22-year-old's third consecutive century against Surrey in championship cricket as he helped the visitors into healthy first innings position of 204 for 2.
At the start of day two, Sussex took a further hour to claim Surrey's three remaining wickets while the hosts added 50 to bag their fourth batting bonus point.
Former Surrey paceman Chris Jordan finished on figures of 5 for 92 - his second five-for of the summer to date.
In response to Surrey's first innings total, Chris Nash (12) lasted an hour on the crease before he was adjudged leg before by a Tim Linley off-cutter.
However, he was left clearly unhappy with Graham Lloyd's controversial decision and marched off showing his bat to the umpire.
Michael Yardy then teamed up with Wells to add 78 in 34 overs. The pair put on 23 runs in just over two hours in a battle of attrition.
The second-wicket stand was eventually broken in the penultimate over before the tea break as left-hander Yardy picked out Rory Burns at leg slip from spinner Gareth Batty.
Wells then joined forces with skipper and fellow left-hander Ed Joyce (51no) to frustrate the home side for the remainder of the day as the pair added an unbeaten 104 for the third wicket stand.