And according to reports in Japan, three deals for players in the J-League are already well down the line as Celtic look to bolster their squad for the second half of the season.
Striker Daizen Maeda has been heavily linked with a move given his connections to Postecoglou, who managed him at Yokohama F Marinos before moving to Glasgow, and media reports in Japan claim that Celtic have agreed a six-month loan for Maeda in January ahead of a permanent summer switch. Maeda, 24, is currently the top scorer in the J-League.
Attacking full-back Reo Hatate, who can also play in midfield, is expected to join Celtic in a deal approaching £1million from Kawasaki Frontale, while the club is also targeting Japan internationalist Yosuke Ideguchi. The 25-year-old midfielder, who had a spell with Leeds United in 2018, is back in his homeland with Gamba Osaka. Capped 15 times by his country, Ideguchi is an energetic, box-to-box midfielder.
Postecoglou has already raided the Japanese market for forward Kyogo Furuhashi, who has been a major hit since arriving in Glasgow.
Celtic are also monitoring the situation between Austrian midfielder Hannes Wolf and Borussia Moenchengladbach. The 22-year-old attacking midfielder joined the Bundesliga outfit permanently from RB Leipzig in the summer, but has failed to break into the first team. Wolf is expected to depart Gladbach on loan next month, with Celtic, Turkish club Trabzonspor and Rapid Vienna in his homeland credited with an interest.