Ahead of New Zealand's crucial 46-32 victory against Newcastle on Sunday, Pompey had been at the centre of a social media storm following a subpar performance against South Sydney the week before.
A flurry of hate comments piled on the centre as social media users levelled criticism of his decisions and defensive mishaps.
When Webster heard about the online disapproval, he was left stunned.
"I didn't know about that. No one told me that. That's probably a weakness of mine," he said.
"I'm not aware of these things, but he didn't show any signs this week. He looked like he was always ready.
"We left him stranded several times last week against Cody Walker. That's their supercar.
"They're idiots, like absolute idiots."
Pompey was relegated from the starting centre role to the bench for Sunday's match but still scored a try and assisted another at Go Media Stadium.
His contributions helped the Warriors virtually lock in a home qualifying final and kept their hopes of winning a first minor premiership in 24 years alive.
New Zealand (40 points, +309) will need to beat Manly on Saturday and hope second-placed Penrith (40 points, +308) lose or win by a smaller margin than them to seal top spot.
Webster will also have to deal with a fresh halves conundrum after debutant Jett Cleary (three try assists, 220 kick metres) and rookie Luke Hanson both shone on Sunday.
The young pair formed the club's ninth spine combination this season as the Warriors are currently without Tanah Boyd (knee) and Luke Metcalf (hamstring).
Halfback Te Maire Martin looked to return from a hamstring injury on Sunday, but the coach opted to play it safe while Chanel Harris-Tavita was also sidelined because of a hamstring niggle incurred during the week.
"We had every intention of Chanel and Te Maire playing (on Sunday)," Webster said.
"No one re-injured anything. Chanel pulled up last week with a tight hamstring. We thought he'd be OK.
"It was just a process where we knew that we were going to send them out there and risk a long-term hamstring injury for both of them ... We had faith in our young guys."
Whether they will return for the all-important clash on Saturday remains to be seen, but the club will sweat on the fitness of winger Luke Laulilii, who failed his HIA on Sunday after a clash with prop Jacob Saifiti.
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