The Bavarians have won the last 11 consecutive league crowns but they needed a Borussia Dortmund slip-up on the final matchday last season to retain it.
Plagued by defensive errors and a low conversion rate in attack since last year's departure of striker Robert Lewandowski to Barcelona, Bayern look to have carried these ailments into the new season.
A 3-0 loss to RB Leipzig in the German Super Cup at home on Saturday left Tuchel, who took over from Julian Nagelsmann late last season, fuming.
"It looks as if we have done no work in the four weeks. I just can't explain it," the coach said, referring to pre-season preparation.
Bayern are still lacking a world-class keeper with Manuel Neuer, recovering from a broken leg he got while skiing in December, still with no comeback date and no top keeper signed for the new season.
A holding midfielder in the six position is the other hole that Tuchel wants to fill before the end of the transfer window.
Bayern signed defender Kim Min-jae from Napoli for 50 million euros to plug those defensive leaks.
As for goals, Tuchel is confident England captain Harry Kane, brought in from Tottenham Hotspur for a league record 100 million euros, will start improving his team's scoring and conversion rate for a winning start.
Kane's German debut, with a low-key substitute appearance in the second half of their Super Cup loss, did little to dampen Bayern fans' enthusiasm and expectations.
Borussia Dortmund's pockets are nowhere near as deep with last season's runners-up having spent less than half of Bayern's transfer outlays, bringing in midfielders Felix Nmecha and Marcel Sabitzer along with Rami Bensebaini.
They will face stiff competition in their challenge to Bayern's dominance from Xabi Alonso's attack-minded Bayer Leverkusen, whose shopping spree netted them Switzerland captain Granit Xhaka, Nigerian striker Victor Boniface and Germany international Jonas Hofmann, among others.
Leipzig have been equally active on the transfer market but it remains to be seen if they have done enough to replace stalwarts Christopher Nkunku, Konrad Laimer, Dominik Szoboszlai, Josko Gvardiol and Andre Silva, who have all left the club.
Their Super Cup win over Bayern gave them an early shot of confidence but they will have to repeat it again on Saturday when they face ambitious Leverkusen in their season opener.
"We can improve many things but this obviously did give us a push," said Leipzig coach Marco Rose of the win against Bayern. "It will be tough against Leverkusen."
Surprise package, Union Berlin have gone all-in with the club's record signing, Robin Gosens, worth a reported 13 million euros, as they prepare for the Champions League group stage after last year's fourth place finish in the Bundesliga.
