Weligton was booked in the first half of the Champions League quarter-final first leg at the Rosaleda and Iturra was shown a yellow card near the end of the game, depriving Malaga of two of their most reliable performers.
Brazilian Weligton is a hugely experienced defender and Chilean Iturra's tireless defensive work helps create the space and freedom for Jeremy Toulalan to dictate play in the middle.
"They are important players," coach Manuel Pellegrini told Spanish television broadcaster Canal Plus.
"Both central defenders already had a yellow card but thankfully (Martin) Demichelis managed to avoid another booking," added the Chilean. "Let's see how we can replace them."
Malaga were under severe pressure from last season's Bundesliga champions in the first half of an entertaining clash on the Spanish south coast.
Goalkeeper Willy Caballero pulled off three brilliant saves to deny the German side and Malaga came close to scoring in the second half when Isco's thumping drive forced a sharp save from Dortmund's Roman Weidenfeller.
"Even though it finished 0-0 I think people would have gone away very pleased with the spectacle they witnessed," Pellegrini said.
"Both teams played an extremely good match trying to push forward into the opponent's half," he added.
"Of course we would have liked to score a goal but the tie is still completely open for both teams.
"There are 90 minutes left and not much will change in Germany from what happened here today. We will go for goal from the start."
Malaga, lying fifth in La Liga, can boost their chances of qualifying for the Champions League again for next season with a win at fourth-placed Real Sociedad on Saturday that would lift them above the San Sebastian-based side.