Rain had limited the final to 16 overs each, with Smith's side limiting Lancashire to 114 for eight before reaching their target with more than an over to spare.

Smith, who will now return to international duty, finished on 64 not out as his side reached 118 for three, with James Hildreth hitting the winning runs.

Smith lost opening partner Marcus Trescothick -- the left-hander caught behind off England teammate Andrew Flintoff for 10 -- but Matthew Wood arrived to take the score past the 50-run mark.

Flintoff then bowled Wood for 22 to leave Somerset 60 for two, and Ian Blackwell followed soon after he was caught by Stuart Law to the first ball of Gary Keedy's spell -- but Smith's innings had brought the rate close to a run per ball.

After losing the toss, Somerset had Lancashire in trouble before Australian Law smashed 59 to give his side a fighting chance.