Portugal attacker Leao has been out of action for the past month with a hamstring injury but Milan are confident their winger will be ready to start at St James' Park and repeat his mesmerising display against Paris Saint-Germain from a month ago.
Leao is Milan's undoubted star man, the player who when on form is capable of turning a match in his side's favour but whose performances have been erratic in a troubled season for the Italian outfit.
Milan will need the version of Leao which tore PSG to bits if they are to have any chance of progressing to the last 16 as a painful home loss to Borussia Dortmund in their most recent group fixture left qualification out of their hands.
Leao has scored four times and set up three more this season but has been criticised for lacklustre performances, his equaliser in the 2-1 home win over PSG his first goal in the best part of two months.
"Criticism spurs me on, keep talking because I'll reply on the pitch," said Leao after the PSG win, which was the last time he found the net as he picked up his hamstring knock a few days later at Lecce.
After the Dortmund defeat which left Milan bottom of the group, Yacine Adli said his team had a "two-to-three per cent chance of qualifying", and making it to the next round is indeed a tall order.
Milan must beat Newcastle, not an impossible task judging by the 4-1 thumping Eddie Howe's team took at Tottenham on Sunday, but also need group leaders Dortmund to beat PSG who are two points ahead of Milan in second spot.
A 3-0 thrashing in Paris in October means that Milan have to finish on more points than PSG otherwise it's relegation to the Europa League or - if they don't win in England - elimination from all continental competition.
Pioli at risk?
And the team is already at a low ebb after Saturday's last-gasp defeat at Atalanta which left Milan nine points behind Serie A leaders Inter Milan and fans calling for coach Stefano Pioli's head.
Pioli has good relations with the club hierarchy and American owners RedBird, and he has a lot of credit in the bank after leading Milan back to the top echelons of the game.
The 2022 Serie A title and last season's run to the semi-finals of the Champions League have been the high points of the post-Silvio Berlusconi era.
He also gets on well with returning idol Zlatan Ibrahimovic, who was key alongside Pioli to re-establishing Milan as a big player.
Ibrahimovic, who called time on his playing career in June, has been brought in as a "senior advisor" by RedBird with a wide mandate which has been met with confusion from fans and pundits alike and led to suspicion that Pioli's job is at risk.
"When he returned to Milan as a player, he was in the dressing room and had an impact there," said Fabio Capello, a four-time Serie A winner with Milan in the 1990s.
"We don't know if he's allowed in the dressing room or if he's allowed to give Pioli hand, nor do we know whether bringing him in will weaken Pioli's authority."
With just three wins from 10 matches since the October international break, Pioli's authority has already been questioned by fans, and he hasn't been helped by a raft of injuries.
Milan are so short in defence that France's buccaneering left-back Theo Hernandez will again have to fill in at centre-back alongside Fikayo Tomori, further placing the onus on Leao to be the miracle worker.
