The 'A Team' hitmaker opened for Swift at the Prudential Center in New Jersey, and later joined the 'Love Story' star onstage to perform their duet, 'Everything Has Changed'.
However, Sheeran's earpiece fell out - leaving the pair struggling to hear each other over the noise of the crowd, reported Us magazine.
The duo lost their places and Swift had to ask her technical team to bring her friend a new earpiece so they could complete their performance.
After the show, Sheeran said, "My earpiece fell out. I couldn't hear in time with the music. I was worried about it but these things happen. We'll move on.