AceShowbiz - Pierce Brosnan was wracked with nerves having to sing in front of ABBA icons Benny Andersson and Bjorn Ulvaeus during a table read for the new "Mamma Mia!" sequel.

The former James Bond star reprises his role as Sam Carmichael, Meryl Streep's onscreen husband, in the new movie musical, and although Pierce had previously put his vocals on display in the 2008 original, he was not feeling confident about his singing abilities as the Swedish pop legends sat in on an early script read-through with the whole cast.

"It was terrifying, utterly terrifying!" he cringed on breakfast show "Today".

"Table reads are the most awkward things anyway," Pierce continued. "I do remember the day, because I was sitting right beside Meryl, and we're all sitting round and there's a lot of company, (we're) knee to knee, with the script, and (we) sang the lines and playing the scenes (sic), and then you have to come and sing (ABBA classic) SOS and there at the music (section was songwriters Benny and Bjorn)...!"

"Anyway, the rest is all history, it's up there on film...!" he laughed.

Pierce wasn't the only one horrified at having to sing with the pop veterans sitting just feet away - cast newcomer Lily James, who portrays a younger version of Streep's Donna Sheridan character, was equally as shy.

"The pressure!" she exclaimed. "It was just so overwhelming, I was burying my head in my script!"

Another new addition to the film's line-up was Cher, who plays Donna's estranged mother, and Pierce reveals even the superstar battled a little anxiety during her first scene on set.

"She was (nervous)," the actor said. "We all do as performers, you need those nerves to carry you through, but you could see her just quiver on the day.

"On that particular day, she was coming onto the set for the first time and the full cast was there. She came in beautifully and embraced us all, and we embraced her right back."

"Mamma Mia! Here We Go Again", which opens in theatres this week (begins July 16), also features the return of Amanda Seyfried, Christine Baranski, Julie Walters, Colin Firth, Stellan Skarsgard, and Dominic Cooper.