I've seen a record 26-trick swing on opening lead, but still, 20 is a lot. Furthermore, this deal swung the quarterfinal match in the 2012 World Championships between USA and Sweden:
Late in the match (the final segment), the USA pair in the Closed Room played 5
X by West down one (looking at all the cards, it can be made). But, the action was in the Open Room:
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