Worcestershire's Daryl Mitchell struck a four off the final ball to earn his side a dramatic tie against Somerset.
The visitors looked to be heading for victory until two wickets in the 49th over from Alfonso Thomas turned the tie back in Somerset's favour.
But, needing five to win, Mitchell hit the boundary that ensured the Royals matched their hosts opening score.
Vikram Solanki and Steven Davies put on a first wicket stand of 181 as they set about overturning Somerset's 298-6.
That partnership came in just 22 overs and set the Royals on course for victory.
However, the Sabres responded and at the start of the final over Worcestershire were left needing 12 runs.
Craig Kieswetter was the mainstay of Somerset's innings as he scored 89, while he was ably supported by Wes Durston (60 not out) and Marcus Trescothick (55).
The result means the threat of relegation still lingers over both sides, with Somerset particularly in danger as they only have one game remaining.
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