Warwickshire, who coasted to victory with a nine wicket win at Worcestershire on Friday, won the toss at Old Trafford and elected to bat.
Trott was the hero on Friday but today he was first man out when he was caught by Katich after only making four runs.
They could not get into their stride and found themselves being restricted by the Lancs attack of Mahmood and Kerrigan.
Neil Carter went for 20, followed by Darren Maddy for 25 to give Kerrigan his first wicket, which he followed up by taking the wicket of Varun Chopra with his next ball.
Warwicks were on 63-4 forcing Skipper Jim Troughton to lead the way with an unbeaten 42 from 34 balls.
Rikki Clarke added ten and Tim Ambrose 15 before the innings ended with Warwicks on 126-6.
It looked an easily achievable target as Lancs put on 48 for the first wicket when Imran Tahir bowled Horton in the last ball of the sixth over.
The leg break bowler had his second wicket when Moore was stumped by Ambrose and took a third wicket when Steven Croft was caught by Darren Maddy.
Katich went for seventeen to see Lancs on 113-4. Then Tom Smith who had made 51 was trapped lbw by Neil Carter to give Warwicks a fighting chance.
Seven runs were required in the final over but they were attained and Lancashire won by five wickets.
On Wednesday, Warwickshire are at home to Leicestershire. Play is due to start at Edgbaston at 5.30pm.