Neil Lennon believes the Scottish Premiership clash with Hibernian at Easter Road on Saturday lunchtime is "pivotal" to a week that also brings the crucial Champions League clash with Ajax.
The Hoops return to domestic duty after the international break three points clear of Inverness at the top of the league table.
The trip to Leith represents a chance to increase that lead, with Caley not playing Partick until Sunday, as well as acting as a tune-up for the visit of the Dutch champions next Tuesday night as Celtic look to put their first European points on the board.
Defeats against AC Milan and Barcelona have dented their qualification hopes, which took another blow on Thursday when skipper Scott Brown was handed a three-match ban for his red card against the Catalan giants earlier in the month.
Celtic confirmed they will appeal after describing UEFA's punishment as"excessive" but in the meantime, the Parkhead boss is looking to build on the convincing home win over Motherwell in their last outing.
He said: "Talking about momentum, (the Hibs game) is pivotal.
"The players have responded to everything that we have asked them to do in the league but if they want to play on Tuesday night they are going to have to play at their best on Saturday.
"It is there for them and it is another great week for us.
"The Ajax game is huge in terms of the group and where we want to be in the group.
"I wouldn't say it is a must-win game, but it is a game we would dearly love to win to get us up and running in the group.
"We mustn't lose. I don't like making predictions but if we could get four points out of the next two games it would set us up very nicely indeed. But it is a big ask."
"The players have responded to everything that we have asked them to do in the league" - Neil Lennon
Lennon praised Hibs boss Pat Fenlon for taking the Easter Road club up into fifth place in the table after their nightmare start to the season, which saw them knocked out of the Europa League qualifiers 9-0 on aggregate by Swedish side Malmo in July.
The former Celtic skipper said: "They have turned things around since the Malmo game where it was all doom and gloom and they have some really decent results, winning at Partick and at St Johnstone.
"We lost at Easter Road last year and Pat's teams can be dogged when they want to be and difficult to beat, so we have to be wary of that.
"Paul Heffernan has been a good signing for Pat. I think he is clever, a goalscorer, and they have a threat going forward with him and James Collins while Liam Craig has had an excellent start to the season.
"But we want to go into the Ajax game with a positive result."