The Norwegian has heaped praise on his coach and fellow countryman.
Deila came under fire for a poor start with the Bhoys earlier this season but steadily turned things around and the Scottish champions are now on course for their first domestic treble since 2001.
On Friday night, Celtic moved one step closer to defending their Scottish Premiership title with a 2-0 win at St Mirren.
James Forrest opened the scoring for Deila's men, before Johansen doubled his side's tally from the penalty spot.
And it's Johansen who reserved the biggest praise for his coach, who also worked with the 24-year-old before moving to Celtic.
The midfielder said after the match that he always had the confidence Deila would come good at Parkhead - now he believes the supporters are seeing the proof.
SJ: "I had confidence in the beginning he would be a great manager for Celtic and we are starting to see that now." (MH)— Celtic Football Club (@celticfc) April 3, 2015
SJ: “We are starting to look fitter, we are having much more of the ball & we are playing with higher tempo." (MH)— Celtic Football Club (@celticfc) April 3, 2015
Celtic now sit a full eight points clear of second-placed Aberdeen, who face Partick Thistle next.
Deila, meanwhile, was full of praise for 23-year-old Forrest for the part he played in the St Mirren win when speaking to reporters after the match.