Atherton shared a fourth-wicket stand of 140 with Graham Lloyd (63), while hitting his third ton of the season, reaching 103 in 97 deliveries as Lancashire beat Durham by 84 runs.
Lancashire made 249 for 7 before dismissing the visitors for 165, with the captain, Mike Roseberry, hitting a top score of 54.
Phil Newport's career-best Sunday League return of 5 for 32 plus Tom Moody's hundred helped Worcestershire beat Essex by 178 runs at Chelmsford - their heaviest Sunday defeat. Essex were all out for 75 while chasing 253 for 6.
Yorkshire, previously unbeaten this season, saw their run ended by Leicestershire with a 30-run defeat at Grace Road as they crashed to 170 all out.
Leicestershire slipped from 167 for 2 to 200 for 7 after Nigel Briers and Vince Wells (79) had shared an opening stand of 90.
Mark Ramprakash added 64 to an unbeaten County Championship century against Hampshire as Middlesex reached 244 for 7 and went on to win by 37 runs at Lord's.Reuse content