Hoops boss Neil Lennon admits he and his scouts have identified the men they want to sign, and are expected to make their moves as soon as they know they have qualified for the group stage of the Champions League.
That can be guaranteed on Wednesday if Celtic finish the job they started last week in the first leg of the play-off in Helsingborg.
Lennon also wants to recruit at least one more striker, and his network of scouts have been working hard to come up with options.
But Yoshida – currently looking for a way out of Dutch club VVV-Venlo – and Ambrose, who plays for FC Ashod in Israel – could be offered the chance to add the extra quality Lennon wants at the back.
SportTimes revealed last month that 24-year-old Yoshida is a player on Lennon's radar. Now VVV-Venlo general manager Hans Soentjens has confirmed he is aware of Celtic's interest and is waiting for an offer for the £2million-rated defender before the window closes this weekend.
He said: "Celtic have contacted us officially to make their serious interest known. We're now waiting for their offer."
However, Soentjens warned: "I know a number of clubs from the Premier League are very interested."
Newcastle, Southampton, Stoke, Aston Villa and Everton are understood to be the English outfits.
VVV-Venlo chairman Hai Berden has given the green light to the sale of their player, and said: "For VVV and Maya this is the perfect moment for him to make the step to a bigger club."
Lennon confirmed that Yoshida's Olympics team-mate, Yuki Otsu – who plays for Borussia Munchengladbach – is a player Celtic like, but said there were no plans to try to recruit the attacking midfielder in this window.
Despite injuries to Beram Kayal and Joe Ledley and the sale of Ki Sung-Yueng to Swansea for £6m, the Hoops boss still feels he is well staffed in the midfield area.
Rosenborg's Markus Henriksen remains the go-to player if the Hoops do decide to add a box-to-box midfielder.
Lennon would also like to add some firepower, and Wolfsburg's Croatian hitman, Srdjan Lakic, is reported to be someone they could try to bring in on loan later this week.
But strengthening in central defence continues to be the priority, and Auxerre's Wily Boly is another man reported to be on the list Lennon is considering, though the 21-year-old is also being tracked by Fiorentina, Lorient and Lille, which would push up his price.
Ambrose is a more viable option, and is bracketed at less than half the price of Yoshida. He is 23, and, like Yoshida, the Nigerian would require a work permit to play. This was what caused Manchester City's interest to cool when they had him on trial in January.
However, Ambrose – whose contract runs out next year – has now become a regular in his national side and is included in the squad for next month's African Cup of Nations qualifier against Liberia.
Nigeria are placed well within the top 75 in Fifa's rankings, so he would be expected to meet the criteria for a work permit in Scotland.