Ryan Patel took six wickets in just 23 balls as Surrey made Somerset follow-on in the top-of-the-table Specsavers County Championship Division One clash.
The 20-year-old had previously only taken two first-class wickets but he ripped through the visitors with six for five to leave Somerset 180 all out, 279 runs in arrears.
The hosts then enforced the follow-on, with Somerset at least able to reach stumps with all of their second-innings wickets intact, even if they still trail by 261 runs having made 18 without loss.
Earlier, Surrey accumulated 459 in their first innings as Ollie Pope top-scored with 117.
Worcestershire, the division’s only winless side, are hoping to claim their first victory against Lancashire thanks to Ed Barnard’s five for 34 and Daryl Mitchell’s second ton of the game.
All five of Barnard’s victims were dismissed without scoring as Lancs slumped to 130 all out in reply to Worcestershire’s 247.
Fellow opener Martin Guptill also reached three figures in an opening partnership worth 215 before Worcestershire ended the day on 361 for four.
At Chelmsford, Nottinghamshire built up a 209-run lead over defending champions Essex.
Having posted 380 in their first innings, Notts then dismissed Essex for 206 – Matt Carter and Luke Fletcher taking four wickets apiece – and elected not to enforce the follow-on before reaching 35 for one second time around.
South African quick Dale Steyn claimed a five-wicket haul in first-class cricket for the first time in two years in Hampshire’s clash with Yorkshire.
Steyn, who is playing county cricket to get back up to speed following a series of injury setbacks, took five for 66 in 29 overs of a Yorkshire innings that ended with the visitors making 350.
Hampshire responded by posting 245 for three by stumps – Jimmy Adams making an unbeaten 132.
Division Two high-fliers Warwickshire are staring down the barrel of their first loss as fellow title contenders Kent built up a commanding lead.
Sean Dickson and Joe Denly, with 133 and 119 respectively, helped Kent to 359 for six in their second innings, which saw their advantage increase to 431 runs.
Durham still have it all to do at Sussex after ending day two 202 for four, still 350 runs adrift of their hosts’ massive first-innings total.
Sussex were eventually all out for 552 and though Durham slipped to 96 for three, Will Smith’s 90 not out has given them hope they can save the match.
Leicestershire are in charge of their contest against Middlesex, with Colin Ackermann scoring a career-best 196 not out at Grace Road.
He ran out of partners when just four shy of a double-century, but still provided a crucial knock in his team’s 427, with Middlesex only able to make 233 in response.
Though Leicestershire lost captain Paul Horton without a run on the board at the start of their second innings, they still had a 194-run lead.
Elsewhere, Derbyshire, who reached stumps on 207 for three, are just 76 runs behind Glamorgan’s first-innings score of 283, while Northamptonshire look set to achieve their first victory of the campaign, with Gloucestershire eight down and having just a 25-run lead in the second innings.