Piers was thrilled after hearing the news that since he and Susanna returned, GMB had seen its highest ratings ever.
He then compared their growing figures to BBC Breakfast, before taking a swipe at Dan by hitting he could soon be jobless.
Piers, 55, said: "The BBC crashed to its lowest ratings of the year on the same day."
Piers said: "If you want to see what affect this has had, this is what Dan Walker - who apparently is still presenting it - this is his selfie this morning."
Susanna replied: "We beat them at moments of the programme."
Piers hit back "If you want to see what affect this has had, this is what Dan Walker - who apparently is still presenting it - this is his selfie this morning."
The show then aired a picture of Dan looking into a mirror with a frown on his face, seemingly in his BBC dressing room.
Susanna joined in as she agreed: "He looks concerned."
Piers then spoke to Dan directly as he said: "If you do lose your job over the ratings - and it can't be long, sadly - if you do... god forbid you do because it needs you there...
"If you do, you won't be able to work at AJ's Unisex Salons unless you start to chirp up a bit! You've got to perk up a bit!"
Meanwhile Piers faced an embarrassing morning on the show as he accused his co-workers of "fat-shaming" him after a series of jibes.
After Piers insisted that being told he was overweight would motivate him to lose it, he faced jibes from Susanna, Dr Hilary, Andi Peters and even his own mum.
You can't win them all...
GMB continues tomorrow at 6am on ITV.