Belgium grabbed a lifeline just before half-time when Romelu Lukaku converted a penalty after Nicolo Barella and Lorenzo Insigne scored first-half goals for the Azzurri in Munich.
The Swiss qualified for their first major tournament quarter-final since 1954 with a stunning win on penalties over reigning world champions France in Bucharest on Monday.
Neither trained Wednesday with Belgium's medical staff working around the clock to get them fit to face Italy.
There had been concern about the extent of the injuries after both players had to be replaced in the second half of Belgium's 1-0 victory over Portugal on Sunday in the round of 16.
Axel Witsel will also play from the start in the game in St.Petersburg in Monday as Martinez looks to give three of his most important and experienced players some extra game time.
The players and spectators paid tribute to Eriksen with a minute's applause after 10 minutes at a Parken Stadium adorned with banners showing supporters' support for Denmark's star player.
Players from both teams halted play after 10 minutes as the 25,000 fans rose for a minute of thunderous applause in tribute to Eriksen.
Belgium’s second game in Group B is against Denmark in Copenhagen on Thursday, when Martinez expects De Bruyne to play a part.
The Manchester City playmaker underwent "a small operation" on his face on Saturday morning after suffering fractures to his nose and left eye socket in a collision with Chelsea's Antonio Ruediger.
With Eden Hazard also recovering from injury, his brother Thorgan took the initiative for Belgium, scoring with his shin in the 20th minute off a cross from Yannick Carrasco.
On paper, at least, because the form of some of the players on the top-ranked FIFA team raises a big question mark on its ability to go deep at this year's European Championship.
The 29-year-old De Bruyne sustained the injuries in a collision with Chelsea defender Antonio Rudiger while playing for Manchester City in the Champions League final on Saturday.
The 29-year-old Belgian playmaker had to be replaced by Gabriel Jesus in the 60th minute on Saturday following a collision with Antonio Rudiger.
Belgium team for Euro Cup: Eden Hazard, Romelu Lukaku, Kevin De Bruyne all included by Roberto Martinez
Martinez also selected a group of 11 reserve players who could step up in case of injuries ahead of the tournament, which opens on June 11.
The Belgian has spent five-and-a-half years at the Etihad, a period which has seen him establish himself as one of the world's finest creative players.