The Lions have a superb chance to reach the FA Cup semi-finals after being drawn against Blackburn in the last eight.
But they have slipped off the play-off pace lately and are currently 13th, nine points shy of the top six, ahead of Tuesday night's visit of lowly Peterborough.
Jackett told the club's website: "The Blackburn match is one to look forward to, but we've got four important league games before that which could have a big bearing on our season.
"We're delighted to have progressed this far in the cup and we'll embrace it when the next tie comes around, but we have worked very hard to get ourselves into a good position in the league and then have dropped off the pace in recent weeks.
"Our priority now is to rediscover our form in the Championship and then hope to take that into the cup tie."
- Sports & Recreation