Nottinghamshire 101 (T Curran 5-28, McKerr 3-21) and 83 for 2 trail Surrey 375 (Stoneman 144, Foakes 48, Jacks 48) by 191 runs
While his younger brother was leading England's flimsy resistance at the Ageas Bowl, Tom Curran added to the impression that Surrey are champions elect as his 5 for 28 forced Nottinghamshire to follow on at the Kia Oval.
Nottinghamshire were bowled out in some disarray for 101 in reply to Surrey's 375 as Curran made a telling impact in his first Championship game of the season. Although they rallied in the final session of day two, reaching stumps on 83 for 2 in their second innings, they still trail by 191.
Surrey - 32 points ahead of nearest rivals Somerset before this round of matches and seeking their eighth win of the campaign - look like taking another significant step towards their first Specsavers County Championship title since 2002.
Ben Slater and Kraigg Brathwaite put on 41 for Notts' first wicket second time around, before Conor McKerr had Slater caught behind for 21, and there was more resistance until off spinner Amar Virdi, introduced just before bad light brought a premature end to the day, seven overs early, had Jake Libby leg-before for 17. Brathwaite is 39 not out.
Tom Moores, with 29, was the top-scorer after Curransent back Slater (9), Brathwaite (2) and Libby (12) in quick succession, while Morne Morkel had Samit Patel leg-before for 5.
Slater was caught behind, Brathwaite leg-before and Libby held at third slip, driving, and Notts were 39 for 5 when McKerr, replacing Morkel at the Vauxhall End, struck in his first over to have Billy Root caught at the wicket by Ben Foakes for 6.
McKerr then saw Riki Wessels (12) slice to point to make it 70 for 6, and just before tea Luke Wood was caught behind for 8 in Morkel's second spell to complete a miserable afternoon session for the visitors.
Moores had just extra cover driven McKerr for a flamboyant boundary when, two balls later, he aimed another big drive to a ball outside his off stump and edged to Foakes, who then took his fifth catch of the innings when Luke Fletcher nicked a drive at the returning Curran. Two balls later, Harry Gurney's stumps were shattered by Curran and Notts' last three wickets had gone in seven balls.
Earlier Mark Stoneman's 22nd first-class hundred helped Surrey to four batting bonus points as they made good progress from their overnight 256 for 6. Opener Stoneman, who resumed on 99 not out, soon reached three figures and was eventually ninth out for 144 having batted for more than seven hours and faced 260 balls, hitting 18 fours.
Last wicket pair McKerr and Virdi completed the task of getting Surrey past the 350-mark with a frisky stand of 35 after Stoneman, looking to cut a ball a little too near him for the shot, edged Wood's left-arm swingers to keeper Moores.
At the start of the day, Stoneman and Curran had taken their seventh wicket partnership to 84 in 22 overs before Curran, who hit some sparkling offside shots in a 69-ball 43 which included five fours, top-edged a hook at Matt Milnes to Root at long leg. The short ball also accounted for Morkel, who skied a flappy pull at Gurney to Milnes at long leg to go for 5.
McKerr finished 19 not out and, immediately after hitting Patel's left-arm spin for six over long on to reach 19, No 11 Virdi was bowled heaving at the next ball.