When a late-night host suffers an injury in the middle of a monologue, who do you call?
If you're "Tonight Show" host Jimmy Fallon, you turn to your predecessor: Jay Leno.
Fallon faked a hamstring injury at the top of the monologue and asked if someone could "tag in" for him. Leno, who has a new show called "Jay Leno's Garage" debuting tonight on CNBC, answered the call.
Check it out in the clip above.
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