Britain's Andy Murray has been forced to pull out of the Madrid Open due to illness, the tournament's organisers have confirmed.
The three-time Grand Slam champion was one of three British men due to be taking part in the third round after progressing past Dominic Thiem and Denis Shapovalov.
Alongside Dan Evans and Cameron Norrie, Murray made history at this year's Madrid Open, with the tournament marking the first time ever that Britain had three men in the third round of a Masters 1000 event.
The 34-year-old was due to renew his rivalry with world number one Djokovic on centre court this morning, but he will no longer participate in the tournament, which he entered as a wildcard after initially announcing his desire to skip the clay court season.
A post by the Madrid Open Twitter account read: "Unfortunately, Andy Murray is unable to take to the Manolo Santana Stadium due to illness 😔 We wish you a speedy recovery, @andy_murray! 😘."
With Murray no longer taking to the court at the Madrid Open, compatriot Evans will instead play on centre court at the Manolo Santana against Russia's Andrey Rublev.
Djokovic therefore receives a walkover into the quarter-finals, where he will meet the winner of Hubert Hurkacz and Dusan Lajovic's third-round battle on Thursday afternoon.
Fellow Brit Norrie - who overcame the USA's John Isner in three sets on Wednesday - will round off the day's action in the men's singles with a meeting with Spanish teenager Carlos Alcaraz Garfia.
Prior to Norrie's battle with Alcaraz Garfia, Rafael Nadal finds himself up against Belgium's David Goffin on centre court, while second seed Alexander Zverev faces off against Lorenzo Musetti.
The women's semi-finals also get underway on Thursday, starting with Ekaterina Alexandrova's clash with Ons Jabeur before Jessica Pegula meets Jil Teichmann.
