Mohsni and his fellow defenders were heavily criticised for their catastrophic performance in the SPFL League One showdown with Brechin City last month.
The Gers rearguard let in three goals in the first 45 minutes of the match up at Glebe Park and trailed 3-1 to their part-time rivals at half-time.
An amazing second-half comeback - capped by a late winning goal from substitute Nicky Clark - ensured the visitors edged the game 4-3 to keep their winning run going.
But the members of the Gers backline vowed that day not to let their standards slip so badly again - and they have been true to their word.
They have not conceded a single goal in three consecutive victories over East Fife in Methil, Stenhousemuir at Ochilview and Airdrie at Ibrox.
Mohsni believes having a settled rearguard has helped Rangers successfully repel their opponents in both the league and in the cup competitions.
McCoist has picked Cammy Bell in goals, Ricky Foster at right-back, Lee McCulloch and Mohsni at centre-half and Lee Wallace at left-back in his side's last three fixtures.
Many Light Blues fans are starting to get excited about the prospect of their team enjoying a 'Perfect Season' and winning all of their league games.
The French-Tunisian player is keen to help the club achieve that ambitious aim - but his immediate objective is to stop Dunfermline netting at Ibrox tomorrow night.
He said: "I am sure anybody watching the Brechin game last month would have thought that it was easy to score goals against Rangers. We made stupid mistakes in the first half and we gave goals away.
"It was strange because we had only conceded two goals in the 10 games leading up to that match. When we concentrate properly we know we can stop the teams that we play against from scoring.
"We have now kept clean sheets in our last three games. That is a good response from everyone in the team -from the centre forward to the centre-back -to our performance against Brechin."
Former Ipswich Town and Southend United player Mohsni has become a cult hero to the Rangers supporters since joining on a free transfer in the summer due to the number of goals that he has scored.
The 6ft 3in 26-year-old has netted six times during the campaign - including a spectacular overhead kick in the 8-0 annihilation of Stenhousemuir at Ibrox back in September.
However, as a centre-half he is primarily concerned with defending and the run of three games that Rangers have gone on without conceding a goal has pleased him enormously.
He said: "Defending is my main job in the team. I know I can score goals. Lee McCulloch is exactly the same. But the most important thing for both of us is to keep a clean sheet. That is the same for Cammy Bell, Ricky Foster and Lee Wallace.
"We have definitely got to know each other better as the season has gone on. The more games that we play the more that we know each other as players. We know when we have to cover, when to push forward, what suits each individual player best, which foot they like to receive the ball on and so on.
"If you play in the same back five every week then it becomes very easy to anticipate what your team-mate will do. We have started the season well and hopefully we should improve as the season continues."
Mohsni, a one-time target for Barclays Premier League club West Ham, has also paid tribute to Rangers captain McCulloch for helping him to settle since he arrived at Glasgow during the close season.
He said: "Lee is a very good player. He talks to the players around him all the time. He encourages us all the time and tells us where to go and when to go there. He is very helpful to everyone around him in the team.
"Having Lee beside me in the team helps me to go upfield and try to score goals. I know that he will be there covering for me if there is an opportunity for me to get forward during a game.
"But, as I say, my job is to defend and that is what I try my best to do to the best of my ability every game."