11:54 AM PT -- Huge bummer for Tayvis -- the singer's second Buenos Aires date was just postponed 'til Sunday due to rain.
Unclear how long Travis Kelce was planning to stay in town ... but we take it he'll just tune in to Saturday's show.
Taylor Swift released a statement on the decision to push back the gig ... saying she loves to perform in uncooperative weather, but didn't want to put her fans in harm's way.
Guess this clears her schedule for a date night with Travis!