Surrey were crowned English county champions for a third straight season on Friday, with Somerset's defeat against Lancashire guaranteeing them the title.
The London-based County crushed Durham by 10 wickets at the Oval on Thursday -- their sixth victory in seven home games in the first-class competition this season.
Somerset needed to beat relegation-threatened Lancashire on the fourth and final day of their match at Old Trafford to stay in the hunt for their first-ever Championship title.
But they slipped to a 168-run defeat and, with one game remaining, can no longer catch their rivals, whom they beat last week.
Surrey are the first team since Yorkshire in the 1960s to win three titles in a row.
Surrey face Essex at Chelmsford in the final round of the Championship, with Somerset hosting Hampshire.