Croft claimed the third try in the 65th minute which provided some valuable daylight between the teams, running in from 50 metres to dot down in the right-hand corner.
“The club has a history of getting through semi-finals and getting to finals but today it was just about this game,” said Croft.
“You have got to get through it, whether it is 6-3 or you pull out in front. It is just about getting this hurdle – and Quins are a big hurdle – out of the way.”
Croft produced a try-saving tackle on Quins scrum-half Danny Care in the first half, while full-back Mathew Tait ended a break from Quins centre George Lowe just short of the tryline before Tigers made the breakthrough with the opening try in the 40th minute.
Tigers claimed three more in a 13-minute spell in the second half and their defence was not breached until Ross Chisholm finished off a length-of-the-field breakaway try for Quins with just three minutes remaining.
“We said at half-time we couldn’t step off and let Quins get a sniff because you can’t afford to let them do that," added Croft.
“Quins are an outstanding side and you have to be on the ball to get the win.
"The boys stuck in, the defence was superb and that is what won it for us today.
“Everyone kept dragging themselves up off the floor and doing the work.”
Tigers captain Toby Flood said: “In terms of the energy and enthusiasm we brought, we probably didn’t get our rewards in the first half. But there are always periods where you are going to be under pressure from Quins with the way they play.
“We gave away a few penalties in succession and that allowed them to build pressure on us.
“We spoke before the game about teams should come to Welford Road and find it a hard place to win, but Quins have not done that in their last couple of visits. We wanted to put that right and the crowd were outstanding today, they are a huge factor in what we are about.”
