"Tonight Show" host Jimmy Fallon greeted Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE at an interview taping on Friday by donning a medical mask after the Democratic nominee took a break from the campaign to recover from pneumonia.

Clinton gave the late-night host a high five.

.@jimmyfallon put on a medical mask to start his interview with Hillary Clinton today. pic.twitter.com/m6KJlSBXZq — Dan Merica (@danmericaCNN) September 16, 2016

Clinton's campaign revealed on Sunday that she had been diagnosed with pneumonia a few days earlier. And video of her seeming to nearly faint as she tried to get into a van after a 9/11 memorial didn't help the conspiracy theories swirling about her health.

Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE appeared on Fallon's show Thursday night. Clinton's interview is set to air Monday.