Mathieu van der Poel is out of the UAE Tour, following a positive coronavirus test for an Alpecin-Fenix team member.
The Dutchman, who led after winning stage one, did not start Monday's second stage, because his team withdrew to "safeguard the race bubble".
"Those who came into contact are self-isolating," said organisers RCS. Riders will be tested on 25 and 26 February.
Tour de France winner Tadej Pogacar has taken the lead after finishing fourth in Monday's individual time trial.
The 22-year-old Slovenian, who rides for UAE Team Emirates, won last year's Tour in spectacular fashion by winning an individual time trial on the penultimate stage of the race.
But on the 13km course on Al Hudayriat Island he could only manage fourth, 24 seconds behind winner Filippo Ganna of Ineos, who won last year's road world time trial championships and continues to dominate top-level time trials.
The United Arab Emirates race was won by Britain's Adam Yates last year after it was ended early following several positive coronavirus tests.
Yates finished Monday's time trial of this year's edition in 34th on his debut for Ineos Grenadiers and is now fifth overall, 39 seconds behind red jersey wearer Pogacar.
Chris Froome, who has moved to Israel Start Up Nation this year, lost more than eight minutes during Sunday's opening stage, with strong crosswinds creating echelons and splitting the peloton.
The four-time Tour de France winner now sits nine minutes 43 seconds behind after posting 83rd place in the time trial.
Tuesday's third stage of seven sees the riders take the 166km route from Al Ain to Jebel Hafeet.
UAE Tour stage 2 result:
1. Filippo Ganna (Ita/Ineos Grenadiers) 13mins 56secs
2. Stefan Bissegger (Swi/EF Education-Nippo) +14secs
3. Mikkel Bjerg (Den/UAE-Team Emirates) +21secs
4. Tadej Pogacar (Slo/UAE-Team Emirates) +24secs
5. Luis Leon Sanchez (Spa/Astana-Premier Tech) +30secs
6. Joao Almeida (Por/Decueninck-Quick Step) "
7. Max Walscheid (Ger/Qhubeka-Assos) +32secs
8. Stefan de Bod (RSA/Astana-Premier Tech) +33secs
9. Daniel Martinez (Col/Ineos Grenadiers) +36secs
10. Matthias Brandle (Aus/Israel Start Up Nation) +38secs
1. Tadej Pogacar (Slo/UAE-Team Emirates) 4hrs 5secs
2. Joao Almeida (Por/Deceuninck-Quick Step) + 5secs
3. Chris Harper (Aus/Jumbo-Visma) +33secs
4. Mattia Catteno (Ita/Deceuninck - Quick Step) +35secs
5. Adam Yates (GB/Ineos Grenadiers) +39secs
6. Neilson Powless (USA/EF Education-Nippo) +41secs
7. Anthony Roux (Fra/Groupama - FDJ) +45secs
8. David Dekker (Ned/Jumbo-Visma) +46secs
9. Michael Morkov (Den/Deceuninck-Quick Step) +47secs
10. Damiano Caruso (Ita/Bahrain-Victorious) +47secs
87. Harry Tanfield (GB/Team Qhubeka ASSOS) +9mins 42secs
88. Chris Froome (GB/Israel Start-Up Nation) +9mins 43secs
106. Mark Donovan (GB/Team DSM) +9mins 57secs