Brendan Rodgers said he was "assessing everything" about his Celtic squad after beginning his second stint at the club with a 6-4 pre-season defeat to J-League champions Yokohama F-Marinos in Japan on Wednesday.

Rodgers made a dramatic return to the Glasgow giants after predecessor Ange Postecoglou left for Tottenham after leading Celtic to the Scottish domestic treble last season.

Rodgers won all seven available trophies during his first two-and-a-half-year stint at Parkhead between 2016 and 2019.

The Northern Irishman said there were "some really good bits" as his team kicked off their Japanese tour in steamy Yokohama, including a first-half hat-trick from striker Daizen Maeda.

But he warned that every player was under scrutiny despite the team winning the Scottish domestic treble last season.

"It's a period of the season where we're only a few weeks in, assessing every player and where we're at," said Rodgers, who watched his team concede a fourth-minute opener following a howler from goalkeeper Joe Hart.

"I think we made a number of mistakes for the goals that we gave away tonight. I'm assessing everything at the moment."

Rodgers praised an impressive performance from Japanese striker Maeda, who extended his Celtic contract to 2027 earlier this month.

Maeda scored eight league goals last season and plundered three more against former club Yokohama in a clinical display.

"Daizen Maeda was exceptional tonight in his performance," Rodgers said of the 25-year-old Japan international.

"Everything that you would want in a striker -- his running and movement and pressing."

Rodgers said the game was "a really good examination" for his team against a Yokohama side midway through their domestic season.

Yokohama won the J-League under Postecoglou in 2019 before the Australian left to join Celtic two years later.

They won the league again last year under current coach Kevin Muscat, a former Postecoglou assistant.

"I think a lot of this is to do with fitness and improving the structure of the team as we go along," Rodgers said.

"All in all, really good exercise and a really good atmosphere. The result isn't the priority at this point so we'll prepare for when it matters."