Neil McKenzie was bowled by David Payne six runs short of a hundred to spark a collapse in which Hampshire lost six wickets for 58 runs and were dismissed for 276 in 87 overs, giving them a five run first-innings lead.
The South African made 94 from 170 balls and took advantage of some wayward bowling to score 14 fours and a six, sharing in stands of 79 and 50 with Bilal Shafayat and Katich.
In reply, the hosts struggled as although Rob Nicol (13) and Benny Howell (36) put on 51 for the first wicket, they lost four wickets for 21 runs, with David Balcombe picking up three of them to leave the home side on 102 for four at the close.
Kent's promotion hopes took a blow as they were bowled out for 226 by Essex on day one at Canterbury.
Michael Powell led the way for the hosts with 62 in a three-hour knock, but in difficult batting conditions David Masters, Graham Napier and Maurice Chambers took three wickets each to put the visitors in charge.
In the nine overs remaining in the day, Essex, who have little else but pride to play for this season, reached 14 without loss and will go into day two trailing by 212 runs.
Phil Hughes' first County Championship century for Worcestershire placed another obstacle in Warwickshire's path at Edgbaston in their bid to regain momentum in the Division One title race.
Winless in their last five matches, the current leaders would have hoped for some respite against second-bottom Worcestershire but the Australian's 135 helped his side to 246, with Vikram Solanki (57) the only other visiting batsman to offer much assistance as Jeetan Patel starred with the ball taking four wickets for 72 runs.
After five games without a win, the leaders would have hoped for an easier ride against relegation-threatened local rivals but left-hander Hughes resisted all their efforts in making an unbeaten 135 in a total of 246.
In reply Warwickshire struggled. Varun Chopra and Ian Westwood were lbw within eight balls from Alan Richardson and the pacey newcomer Chris Russell. Richardson also had William Porterfield taken in the slips before the troubled hosts closed at 19 for three.
Bottom club Durham are close to securing their second County Championship victory of the season after dominating against Surrey at Chester-le-Street.
The visitors closed the day on 69 for five in their second innings - still 112 behind the home side's first effort.
Paul Collingwood (78) and Dale Benkenstein (69) both made their best score of the season for Durham and it was their fifth-wicket stand of 132 which put the hosts in command.
Phil Mustard chipped in with 46 as Durham gained three batting points after totalling only two in the five previous home matches. Only opener Rory Burns provided much resistance for Surrey, surviving for 36 overs to reach 28 as Ben Stokes added to his four-wicket haul in the first innings with two more before the close.
Alfonso Thomas took two wickets for Somerset on another rain-ruined day of the potentially important top flight clash against title-chasing Nottinghamshire at Taunton.
Only 15.4 overs were possible following just 8.1 on the first day and the visitors progressed from 18 for one to 48 for three, losing Michael Lumb for 16 and Alex Hales for 12.