Wolfsburg manager Steve McClaren could fine midfielder Diego for disobeying instructions not to take a penalty in Saturday's 1-0 defeat to Hannover.
The Brazilian seized the ball from designated penalty-taker Patrick Helmes and then struck the spot-kick against the crossbar 10 minutes from time.
Former England boss McClaren is under pressure in his first Bundesliga season, with Wolfsburg sat in 12th place and just one point above the relegation play-off spot.
"We had agreed it would be Patrick Helmes and we had announced that (to the team). He has defied us. He should not have taken the penalty," said McClaren.
"We need to discuss this incident."
Germany's Bild newspaper said Diego could be fined €100,000 (£84,000) and be dropped from the team. Club officials could not be immediately reached for comment.
Helmes was signed in the January transfer window with some of the funds from the sale of Edin Dzeko to Manchester City and the 26-year-old is pleased with the opportunity.
The former Bayer Leverkusen striker told Wolfsburg's official website: "Thankfully Bayer Leverkusen acted extremely fairly in those negotiations regarding a transfer.
"But Bayer Leverkusen is a done chapter for me. I am now with Wolfsburg and I am glad about that."