Dylan Hartley admits he is in the last chance saloon with England following his 11-week ban for verbally abusing referee Wayne Barnes in last season's Aviva Premiership final.
In the end, both Lancaster and Mallinder stood by the firebrand hooker, assured that Hartley had learned a tough lesson and would not step out of line again.
Having previously served lengthy bans for biting and gouging, Hartley knows that one more incident would spell the end of his international career and the chance to represent England at a home Rugby World Cup in 2015.
Hartley told BBC Radio Northampton: "I'm extremely thankful for the chances I've had with various coaches.
"With Stuart Lancaster, Graham Rowntree and Jim here at the club - [there are] loyal people sticking with me. But I can't let them down.
"Especially with Stuart, if there's anything else, it's the end of the road for me with England.
"I understand it can't be blind faith. I let Saints down because I wasn't there when they needed me.
"That will always hang over me. If we'd had 15 men on the field, we would've won that final."
Hartley offered to stand down as Northampton captain. After long discussions, Mallinder was convinced that he remained the best man to captain the Saints.
"We didn't jump to it [the decision]," Mallinder said. "We took a lot of time to decide what was the right thing. I spoke to a lot of people, the coaches and a lot of the senior players and Dylan for a long time.
"He has captained the side for the last four seasons and he is an outstanding leader.
"In big games in front of 80,000 people there is a lot of stress on everybody concerned and what happened shouldn't have happened, but we all make mistakes. We learn and move on and make sure our mistakes don't happen again.
"It was a hard lesson to learn but I think he will learn that lesson."
Hartley was sent off and banned for calling referee Barnes a "f****** cheat" after a scrum collapsed shortly before half-time in Northampton's 37-17 defeat at Twickenham.
Just two minutes earlier, Barnes had cautioned Hartley he would take action if the player made any further comments the referee felt were directed at him.
"I apologise for the outcome but when I, hand on my heart, know what I said and who I directed it at, I find it hard to apologise for that," Hartley said.
"But I can see, having been through the disciplinary process, I can see how it was interpreted and I've received a ban.
"You go through different stages of reflecting, a bit of mourning maybe, you're a bit upset then you re-focus and I've been through all that. I want to make a good impression come the start of the season."