Middlesex approach day four of their LV= County Championship fixture against Somerset the more likely team to force a victory, as opener Nick Gubbins once again impressed.
Leeds/Bradford MCCU student Gubbins reached the close of day three unbeaten on 67, to go alongside his first innings 59, as Middlesex closed on 169/2 in their second innings - a lead of 243 over the visitors.
The 20-year-old also made 54 in his Championship debut for Middlesex at Lord's last month.
Dawid Malan followed up his ton in the first innings with 48 from number three for the hosts, while Eoin Morgan reached 42 not out by stumps.
Nick Compton earlier fell six short of a century when he was caught by Tim Murtagh off the bowling of Steven Finn to his 278th ball of a patient knock.
The dismissal was the ninth of the Somerset innings, but captain Marcus Trescothick showed the intent of his title chasing side to go for the victory by declaring when still 74 runs behind.