Surrey 143 for 7 (Pope 68, Barker 3-28) trail Hampshire 149 (Clarke 5-21) by six runs
Ollie Pope pushed his case to be a part of England's winter Test plans with a sublime half-century on a day when fast bowlers excelled at the Ageas Bowl. Batsman Pope, who played two Tests last summer, backed up his 221 not out in his last Specsavers County Championship appearance with a stand-out 68 for Surrey, to take his season average to 120.
On a green-tinged wicket which provided plenty of swing, Pope stood a class above, alongside veteran allrounder Rikki Clarke - who remained unbeaten on 35 at the end of the day, having produced his seventh career five-wicket haul. It was a day of milestones for Clarke, who also claimed his 500th first-class scalp and 11,000th run.
Clarke has enjoyed facing Hampshire in the past two seasons having taken 5 for 29 at the Ageas Bowl last season and 7 for 74 earlier this year at the Kia Oval.
Hampshire, who had won the toss and elected to bat, survived a testing first hour, albeit Ian Holland was dropped without scoring at third slip and Morne Morkel rattled through five successive maidens. But the introduction of first-change pair Clarke and Jordan Clark decimated the hosts' top order - with their morning spell seeing five wickets fall for 31 runs.
Clark needed only six balls to tumble Holland's off stump before Clarke had Felix Organ caught flashing to third slip and Tom Alsop castled in successive overs - as the Hotel End went 9.3 overs before seeing a run.
Veteran Clarke then claimed his 500th first-class wicket, which coincided with his 450th Championship scalp, when Sam Northeast pushed to second slip, leaving Hampshire 26 for 4. James Vince attempted to fight the swing by smashing a six over square leg before producing back-to-back boundaries - but Clark had the last laugh as Jamie Smith hung on at point.
Conor McKerr had Liam Dawson caught behind soon after lunch, before Clarke completed his five-for when the enterprising Aneurin Donald's leading-edge landed at mid-off and Keith Barker was caught at gully.
Kyle Abbott and Lewis McManus provided some rearguard action for the hosts as they put on 45 for the ninth wicket - before the former was bowled by Clark, who bagged 3 for 50, and the latter was lbw to Morkel to conclude the innings.
Surrey's batsmen didn't find the conditions any easier to battle through as they collapsed to 37 for 3 and 61 for 5. Fidel Edwards made the breakthrough in the sixth over when, unlike the pattern of wickets of the day, he bounced Mark Stoneman out, with Vince pouching a simple catch.
An over later Dean Elgar edged Abbott behind, before Scott Borthwick and Smith both poked Barker to Dawson at second slip.
England hopeful Ben Foakes was the next to depart to give Barker his third. But Pope, along with Clarke, hurried the scoring along with a 72 stand for the sixth wicket, with several eye-catching shots nestled among some clever running.
Pope departed in the twilight when Holland had him lbw, before McKerr was leg-before to Abbott to the last ball of the day - Surrey still behind but by just six runs.