If you love a cappella, well, this is your lucky weekend.

The Mohegan Sun Arena is hosting not one but two of the best a cappella groups singing today.

First up is Straight No Chaser on Friday, followed by Saturday and Sunday gigs by Pentatonix. 

In case you need help discerning between the two ensembles, here are some helpful hints.

Straight No Chaser is an all-guys group that first made an impression with a Christmas song — the 1998 video of “The 12 Days of Christmas.” They haven’t skimped on the holiday tunes since, with their most recent album being 2016’s “I’ll Have Another … Christmas Album.” In other words: They have plenty of seasonal material to sing when they bring their tour to the Sun.

Pentatonix, which consists of five singers (four men, one woman), won the NBC show “The Sing-Off” in 2011. They just released their fourth holiday collection, “Christmas Is Here!” Guesting on the album: Kelly Clarkson and Maren Morris.

Straight No Chaser, 8 p.m. Friday, Mohegan Sun Arena; $30; 1-800-745-3000.

Pentatonix, 7 p.m. Saturday and Sunday, Mohegan Sun Arena; $45, $65; 1-800-745-3000.