Andy Murray today withdrew from the Barclays Dubai Tennis Championships after coming down with a virus.
The British number one, and world number four, was due to meet France's Richard Gasquet in the quarter-finals but pulled out shortly before taking the court.
Murray has also been suffering from an ankle injury which forced him out of last week's Open 13 event in Marseille and affected him in his first-round win over Sergiy Stakhovsky on Monday.
Murray had powered past Frenchman Arnaud Clement in the second round yesterday but revealed he then had a rough night, and explained his health had not been at its best since the Australian Open.
The Scot won the ABN AMRO World Tennis Tournament in Rotterdam earlier this month, but said today: "I've not been feeling particularly well since Australia."
He said on Sky Sports News: "Last night after my match, I felt really bad.
"I had some antibiotics from the doctors, (which) didn't really help too much.
"I woke up this morning sweating and I went back to bed for another three hours from 12pm to 3pm.
"Nothing has worked so far."
Murray plans to return to his London base and will allow himself some relaxation time.
He said: "I'm going to try to take a few days off.
"I'll probably go home tomorrow.
"I just need to rest.
"I've obviously played a lot of tennis in the last few weeks and months.
"I hope I'm going to feel better in the next week or so."