Lewandowski, who has netted 35 times in the league this season, is hoping to hit the ground running in the last four matches as he chases Gerd Mueller's all-time Bundesliga record of 40 goals in one season in 1971/72.
For Flick, however, securing their ninth consecutive league crown on Saturday is the top priority. Bayern are in top spot on 71 points, 10 ahead of second-placed RB Leipzig.
For all their injuries, their starting line-up was still impressive, and with Thomas Mueller leading from the front and co-ordinating their suffocating press, Bayern took the game to their hosts.
The French champions advanced from the last 16 with a 4-1 away win in the first leg against Barcelona before suffering in the return leg at home in a 1-1 draw.
"It is something we will have to look into at the end of the season but let's hope things start turning around tomorrow."
The Portuguese headed in a Filip Kostic cross at the far post for his 22nd league goal of the season to lift Frankfurt to 50 points in fourth place, seven ahead of Borussia Dortmund in fifth.
The top four teams qualify for the Champions League group stage.
The Bundesliga's top scorer suffered a knee ligament injury while on international duty with Poland last week and is expected to be out for four weeks.
The Pole has scored 35 league goals and was on track to break the record 40-goal haul of Gerd Mueller from the 1971/72 campaign.
Moenchengladbach, who have lost all seven games since it was confirmed Marco Rose will leave to coach Dortmund next season, can end their dire run at bottom side Schalke on Saturday.
Flick was impressed with Wednesday's 2-1 win which gave the German and European champions a 6-2 aggregate victory over the Serie A side as Bayern reached the quarter-finals for a record 19th time.
"The way we played football is how I imagine it," Flick said after Bayern strolled into the last eight.
Spaniard Guardiola spent trophy-laden seasons with Barcelona and Bayern Munich before joining City ahead of the 2016-17 season and has since guided them to two league titles, three League Cups and the FA Cup.
"I had incredibly hungry teams in my career, lucky to be together in Barcelona and Bayern. To do what we've done in these four years, still winning ... these guys have something special," Guardiola told reporters.
Bayern have won six titles in the past nine months but have stumbled in their last two league matches with a 3-3 draw against visiting Arminia Bielefeld and a 2-1 defeat on Saturday by Eintracht Frankfurt.
"We know what has happened in the past days," Flick said on the two matches last week. "Against Lazio I want us to be there as a team from the start.
"Given the lies that have been spread online in relation to what I said to the female officials during the Club World Cup final medals ceremony, I would like to issue a clarification," the head of the global soccer body said in a statement
"We're very happy about Musiala's development, he's very calm on the ball and the football world can look forward to what will come of this young talent," Flick said recently.