Polish referee Szymon Marciniak is the man responsible for taking charge of Tuesday's Champions League tie between Real Madrid and Chelsea while Slovenian official Slavko Vincic will be the official for Bayern Munich's clash with Villarreal.
Marciniak will have Pawel Sokolnicki and Tomasz Listkiewicz as his assistants, Srdjan Jovanovic of Serbia as his fourth official and Polish official Tomasz Kwiatkowski will be the VAR.
Marciniak, 40, was born in Plock and has been an international referee since 2011. He took charge of Real Madrid's 0-3 win away to Sheriff and refereed a total of six Champions League matches so far this season.
Madrid won 1-3 at Stamford Bridge in the first leg so Ancelotti's men have a good cushion.
Vincic will be do the Bayern versus Villarreal game. Tomaz Klancnik and Andraz Kovacic will be the assistants while Matej Jug is the 4th official. Massimililiano Irrati of Italy is the VAR.
The Slovenian, 42, who has been an international since 2010, has refereed Atletico Madrid on two occasions this season. They were against AC Milan and Man Utd. This term he has taken charge of seven Champions League fixtures.
Villarreal got a surprise 1-0 victory in the first leg so Bayern have work to do back on home soil.