Tonali is currently under investigation by Italian prosecutors and the Italian Football Federation in relation to illegal betting activity, and he is at risk of a lengthy ban from football.
According to Sky Sports News, the 23-year-old's legal team have been working on a plea bargain after the midfielder admitted to betting on his former club AC Milan to win matches during a court hearing in Turin last week.
An agreement over the length of Tonali's suspension is said to be close, with the Italy international potentially receiving a ban which would see him miss the rest of the 2023-24 season and Euro 2024.
Tonali came on as a second-half substitute in Newcastle's 4-0 win over Crystal Palace in the Premier League last weekend, and Howe has confirmed that the midfielder is once again available for selection on Wednesday.
Speaking at a press conference on Tuesday ahead of their Champions League clash with Dortmund, Howe said: «Sandro is fit and fine. Obviously there's things going on, but it's the same as he was before the Crystal Palace match.
»As far as I'm aware, I'm expecting him to be available for tomorrow."
«I'm in a position where I'll plan like that until I'm told differently. I can't second guess what's going to happen,» Howe added. «He's trained today and he's available. I've heard very little as I've been preparing for the game and will wait on anything concrete coming through.
»I've not spoken to him. It was very emotional for him at the end (of the Palace game) and it was clear to see for everybody. But it will help
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