There was nothing to separate the two countries during their 20 overs, with both posting a score of 139.
It was the former of those two batsman who claimed the majority of his side's runs, sweeping one for four and lifting another into the crowd for six off the bowling of spin merchant Marlon Samuels.
Along with McCullum, Ryder helped the Kiwis post a total of 17 runs from their six balls.
Samuels returned to the pitch with Chris Gayle as the Windies went about reaching the victory target.
The West Indies got off to the perfect start when a no ball from Tim Southee was sent for six by Gayle, putting the Caribbean nation on seven runs with just one ball bowled.
That put the Windies in command and a six from Samuels with two balls remaining gave his side a chance of reaching the final four.
Victory for Sri Lanka over England later today will book their place in the semi-finals, while an England win will eliminate the Windies.