Last weekend’s 5-1 humiliation at Torino was Samp’s third defeat of the campaign and their heaviest loss of the season.
The outcome in Turin dropped Samp to fifth place, five points adrift of Napoli, who are third and hold the last Champions League qualifying spot.
“I apologise to our fans for this performance,” Mihajlovic told the Italian press. “I am the first person responsible for this spectacle, but my players must also take a long, hard look at themselves.
“I am ashamed of this performance.
“If I had to start discussing what my team did wrong, we would still be here tomorrow.”
Mihajlovic doubled this week’s training sessions as punishment for his team’s performance.
The good news for Samp fans is that Mihajlovic and recent signing Samuel Eto’o have patched things up.
Eto’o, who made his Samp debut at Toro, had a heated exchange with Mihajlovic and skipped Monday afternoon’s training session.
However, the former Everton forward, returned to training on Wednesday and will make his first appearance at the Luigi Ferraris stadium against Sassuolo.
Samp are unbeaten at home this season and take on a Sassuolo side that travels to Genoa without attacking trio Simone Zaza, Domenico Berardi and Nicola Sansone, all suspended.
Zaza, Berardi and Sansone have combined to score 17 of Sassuolo’s 27 goals so far.
Sassuolo coach Eusebio Di Francesco is expected to field Antonio Floro Flores alongside Sergio Floccari in attack.
The Emilia-Romagna outfit has lost just one of its last six league games and beat Inter Milan 3-1 triumph last time out to climb to 11th place, 10 points clear of the drop zone.
The hosts will be without Argentinian defender Matias Silvestre, who must serve a one-match ban this weekend.