The pair are set to sing Everything Has Changed, the new single for American country star Taylor here in the UK.
The live final is on Saturday 8th June, when it will be revealed which act viewers have picked to win a life changing £250,000 and a spot at this year’s Royal Variety Performance.
There will be eleven acts who make it to the last live show, two from every live semi-final and one extra wild-card act, expected to be chosen from the semi-final's third placed finishers.
And it'll be the public alone who decide the outcome, not that the judges have exactly been good at doing that so far anyway, sending two of the three semi-final decisions to deadlock.
The semi-finals continue tonight with dancers AJ and Chloe, singer Alex Keirl, youngster Asanda Jezile, musical Chasing the Dream, variety group The Clubtown Freaks, impressionist Francine Lewis, illusionist James More, body popper Poppin Ron and all female dance group the Shockarellas.
Olly Murs will perform on the results show from 9:30PM.
Last year's BGT winners Ashleigh and Pudsey meanwhile will return to the series tomorrow night for a performance on the fifth and final of this week's live shows.