The Vatican on Thursday opened the most solemn period of Holy Week with a recovering Pope Francis largely on the sidelines, as cardinals were designated to take his place presiding over the most important liturgical services leading up to Easter.

Pope Francis made his first public appearance since being discharged from hospital two weeks ago after treatment for double pneumonia, entering St. Peter's Square at the Vatican in a wheelchair on Sunday to greet cheering crowds.

Holy Week is a time when the pope would be expected to be front and center of events. But as Francis continues to recover from double pneumonia, observers are on the lookout for surprise appearances.