Michael Carberry hit an unbeaten half century to put Hampshire in the ascendency on day one of their County Championship Division Two clash with Glamorgan at the Rose Bowl.
The England batsman racked up only his second score of 50 or more this season, ending the day on 62 not out in the hosts' 119-1 in reply to Glamorgan's 224
His second-wicket partnership with Liam Dawson (37 no) was worth 87 and left his side 105 runs behind.
Kyle Abbott, Matt Coles and Sean Ervine earlier claimed three wickets each, Ervine returning marginally the best figures of 3-36.
Captain Mark Wallace made an unbeaten 67 for Glamorgan, but their total after losing the toss and being put in to bat looked well short.
A total of 16 wickets fell on the opening dat at The Oval - all to seam bowlers - as Surrey closed on 118-6 in reply to Gloucestershire's first-innings 168.
Matt Dunn claimed 5-48 - his second five-wicket haul of the season - as Gloucestershire lasted only 56.4 overs after being sent in, No 3 William Tavare top scoring with 59.
Gloucestershire had been going along nicely at 100-2 before Alex Gidman's dismissal - lbw to Dunn for 13 - started a collapse of 8-68.
Surrey slipped to 62-6 in response, including 4-38 for James Fuller, before Jason Roy (44no) counter-attacked alongside Chris Tremlett (19no) during the final hour of the day.
The seventh-wicket duo shared an unbroken 56-run stand to reduce Surrey's deficit to 50 by stumps.
Meanwhile in Derby, rain put paid to any chances of play on the first day of Derbyshire's match against Kent.
Several inspections took place before an early tea was called at 3.10pm, and the decision was ultimately taken to reconvene on Monday morning.