Cornwall's hopes of retaining the Minor Counties Trophy took a major blow after they lost by five wickets to Dorset.
Batting first, Cornwall made 283-4 after openers Matt Robins (87) and Matt Rowe (97) had put on 145.
But Lewis McManus' 135 for Dorset, as part of a 153-run opening stand with Mansoor Khan (70), helped the hosts to 286-5 with an over to spare.
Cornwall must beat Oxfordshire in their final game to stand a chance of making the quarter-finals.
If the Duchy win their last match and Devon fail to win both of their remaining fixtures then they will finish second in the group.
After beating Devon in their opening game, Cornwall's second match against Berkshire was rained off.