The theme was Best of British, so District3 opted to cover the emotional Eric Clapton classic Tears In Heaven and Union J chose Coldplay's hit Fix You for their performances.
Both groups, mentored by Louis Walsh, decided to go for the stripped back approach and focus on showing off their vocals.
While District3 were in the bottom two last week, they seemed to redeem themselves in at least the judges' eyes.
Tulisa said it was her favourite performance by the band so far, while Nicole got emotional when praising the song choice.
But there was a sting amid the praise from Gary Barlow, who credited their vocal skills.
"If I'm sat in a record label right now looking for the next big boy band, is it you? I don't think it is," he shrugged. "There's something that slightly dated about this band. I don't know what it is. There's something that's just not got the edge that Union J have..."
Union J's performance also went down well and the song choices of both groups were noted as working in their favour.
One thing they may have to worry about though is appealing to the same demographic.
As Tulisa pointed out, the battle of the boybands could split the vote.
"I can't call it," she said.
Meanwhile, strong contender for the final Jahmene Douglas picked the Robbie Williams track Angels, which could have been a risky move - given that it's frequently tackled, not usually with much success, on talent shows.
But the shy former supermarket worker once again blew everyone away with his gospel choir-backed rendition of the song.
"Angels has been sung in talent shows hundreds of times - but never like that!" Gary, Robbie's own bandmate, said.
From the sublime to the ... spicy, Rylan Clark fulfilled a dream ambition by performing a Spice Girls medley in a jacket reminiscent of that Geri dress.
His harness might have gotten a bit stuck when he parachuted - yes, parachuted - onto the stage, but even his nemesis Gary loved it. Sort of.
"On the subject of fun, that was absolutely brilliant," Grumpy Spice declared.
"But on the subject of vocals, that was absolutely diabolical."
The long-running saga over Christopher Maloney's suitability for the competition, given his penchant for dated classics, continued - with Nicole Scherzinger branding him the "karaoke king".
For the last remaining girl Ella Henderson, a cover of Tinie Tempah's Written In The Stars let her mentor Tulisa's "little star" shine.
Louis Walsh did say she could be the best girl on the X Factor since Leona Lewis, but he wasn't sure about her song choice.
"Because you wouldn't know Tinie Tempah from Tiny Tim, Louis!" Tulisa hit back.
With it falling to James Arthur to perform last, his angsty performance of Hometown Glory saw him once again draw praise from the panel.
"No one should ever cover Adele songs," Gary said. "Except you."
Find out who ends up in the bottom two and who exits the show in Sunday's X Factor results show on UTV at 8pm.