Joe Root made up for his first-innings failure as he demonstrated timely form for Yorkshire in his comeback match against Middlesex at Lord's.
Root, out of action with a broken thumb until returning in a second XI fixture last week but hoping to be involved in England's one-day internationals against Scotland and Sri Lanka, made a duck at the first attempt back in the LV= County Championship Division One.
On day two, however, he not only avoided the dreaded pair but contributed 63 to the cause before falling lbw to Steven Finn (three for 59) as Yorkshire added 213 for four to the 55-run lead already in the bank after bowling the hosts out for 123.
Ryan Sidebottom (four for 34) was their most successful bowler, before opener Adam Lyth (54) gave the White Rose a sound start second time round - and Root then top-scored.
Two late wickets kept Warwickshire's noses just ahead in an intriguing match against Nottinghamshire at Trent Bridge.
Only the dismissals of Michael Lumb and then Phil Jaques, after their stand of 92, made Warwickshire marginal favourites as the hosts reached 126 for three in pursuit of 300 to win.
Nottinghamshire conceded a 147-run deficit when they were bowled out for 116.
But Warwickshire could augment their advantage with only 152 all out - and then Jaques (64) and Lumb kept all results possible in a topsy-turvy match set to finish inside three days.
At Hove, Somerset captain Marcus Trescothick's first century since 2012 helped his team to 372 all out against championship leaders Sussex.
Veteran former England opener Trescothick (116) reached his 52nd first-class hundred in exactly five hours, and shared a fifth-wicket stand of 139 with Alviro Petersen (76).
Chris Jordan finished with figures of five for 76 for the hosts, who were 25 for one at stumps.
At Wantage Road, promoted pair Northamptonshire and Lancashire - both seeking a first win of the season - are engaged in their own tight tussle.
James Anderson was unable to add to his first-day five-wicket haul as Matt Spriegel (62) helped the hosts to 164 all out and a 45-run lead.
But Lancashire's second innings then reached 244 for five thanks to an unbroken stand of 114 between Jos Buttler (66no) and Tom Smith.
In Division Two, play finally got under way at Bristol after a first-day washout and another delayed start.
Ball largely dominated bat, Essex seamer David Masters taking four for 39, as Gloucestershire struggled to 104 for six.
James Vince had time before rain returned on another wet day on the south coast to hit a near run-a-ball century for Hampshire against Surrey at the Ageas Bowl.
He shared a century stand with his captain Jimmy Adams (65) and was still unbeaten on 118 out of 289 for three when play was abandoned after an afternoon downpour.
At Grace Road, Leicestershire wicketkeeper Niall O'Brien (133) top-scored as the hosts racked up 500 against Glamorgan - thanks also to Rob Taylor (63) and Jigar Naik (59no) down the order.
O'Brien hit 14 fours and two sixes from 141 balls, and there was also a half-century for captain Josh Cobb (63).
The visitors, for whom Graham Wagg had taken four wickets, then ran up 126 without loss after half-centuries from Jacques Rudolph (63no) and Gareth Rees (53no).
At New Road, Derbyshire captain Wayne Madsen (111no) dug in from number three to help his team to 219 all out after they began on three for two following the 3.5 overs possible on Sunday.
Worcestershire, for whom Saeed Ajmal took four for 60, then closed on 31 without loss.