Bayern have lost only once in their last 14 top-flight outings, and are on a four-game winning streak.
Champions Bayern Munich will kick off 2018 with an nearly complete squad after top scorer Robert Lewandowski, Mats Hummels and Joshua Kimmich were declared fit before their Bundesliga campaign resumes against Bayer Leverkusen on Friday.
In the same breath, the many-time German champions will be keeping a close eye on explosive Leverkusen's Jamaican winger Leon Bailey, who has made a name for himself in the first half of the season with six goals and four assists. Bayern are comfortable atop the table, 11 points clear of second-place Schalke and 13 points ahead of fourth-place Bayer Leverkusen.
Leverkusen warmed up for Bayern with a 2-2 draw in a friendly against third-tier Preussen Muenster as Argentina striker Lucas Alario netted both goals following his recovery from a groin injury.
The Poland star is returning to full training after a knee injury, but Heynckes opted to start Thomas Mueller up front for Bayern at Leverkusen with Wagner on the bench.
Bayern stepped up their preparations with a 5-3 win over third-division Grossaspach on Tuesday when veteran winger Franck Ribery, 34, scored three goals in a starring display.
Heynckes was the last Bayern coach to win at Friday's opponents Bayer Leverkusen, but that was in his previous spell in charge back in 2013. Neither of them are in the squad, " said Heynckes, before adding that German worldwide Wagner is the "first option" to replace Lewandowski in attack but far from certain to start.
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Likewise, Bayern are trying to talk Heynckes into staying on as head coach past the end of the season.
Bayern were five points adrift in the league when Heynckes, 72, replaced Carlo Ancelotti at the start of October, but built up a commanding lead as key rivals RB Leipzig and Borussia Dortmund faltered.
To the surprise of Bayern fans, it was the away side who took the lead through defender Carsten Ramelow. "If we all stay fit that will definitely help, but we also need good combinations, lots of movement off the ball, plus to mix up the tempo".
"We have to play better with the ball, but we won 3-1, that was important".
With Lewandowski out, burly Germany striker Sandro Wagner is set to make his first Bundesliga appearance since joining from Hoffenheim last month, reportedly for 12 million euros ($14.3m).
Javi Martinez (L) of Bayern Munich vies with Kai Havertz of Leverkusen during the German Bundesliga soccer match between Bayer Leverkusen and Bayern Munich in Leverkusen, Germany, Jan. 12, 2018.
The 46-year-old later said he was ashamed of his actions after dramatically tumbling to the ground after faint contact with Gladbach's Denis Zakaria in the technical area.