Millwall boss Kenny Jackett said their FA Cup run can help their Championship quest following Saturday's comfortable 3-0 win over Luton.
The Lions had few problems in seeing off the non-league battlers at Kenilworth Road with James Henry, Rob Hulse and Dany N'Guessan all getting on the scoresheet.
And with the prize of a last-eight spot, it was welcome relief from league duties with the London side currently in 12th, nine points from the play-off zone.
Jackett said: "We're very pleased to be in the quarter-final of the FA Cup, it's a great achievement. If we can get a home tie that would be fantastic.
"It's a fantastic opportunity to finish the season well. We want to get back on track in the Championship, we've lost our way, but performances like this will help.
"Scoring the first goal was key, if Luton got the first it would have been tough for us. It was a tough atmosphere today and we did the job very professionally."
Henry's opener in the 12th minute helped quieten the home fans and he added: "It settled all of us down and brought our fans into play, and we pushed on from there.
"They pushed us all the way, at 1-0 they had a good chance, but we just had that little bit of extra quality. It's a great result for us.
"We knew it was going to be a really difficult game and we're delighted to be in the last eight. We're one game away from Wembley now so we'll take anyone."
The 25-year-old has not featured for the Shrimpers this season after he was shipped out on loan to Championship outfit Ipswich.
But with an ever-increasing injury list at Roots Hall, manager Paul Sturrock has recalled the versatile player and rewarded him with a start against the Cobblers.
Mohsni told the club's official website: "First of all I would like to just apologise to everyone at the club for what has happened in the past.
"The manager and I have spoken about returning to the club. The manager has always been very good with me and I have returned to repay the faith he has put in me.
"Hopefully I can play a big part in helping the club after all the injuries they've suffered over the last few weeks."
Sturrock added: "Bilel has returned in a time of need because with all the injuries we are really struggling.
"He and the club regret what has happened in the past. Bilel is a maverick but he is a good man and a very good player and with all the injuries we have he will be a big help."
