Last year Sea The Stars made racing history by becoming the first horse to win the 2000 Guineas, The Derby and Prix de l’Arc de Triomphe.
Zarkava was scanned and shown to be in foal at 15 days last weekend (Sunday 21 March).
If everything progresses to plan the arrival is expected in early 2011.
The 2008 Arc de Triomphe winner gave birth to her first foal, a filly by Group one winner Dalakhani, on 6 February.
Sea The Stars, who retired to the Aga Khan’s Gilltown Stud in Co Kildare last October, is estimated to generate around £10m a year in stud fees.
He stands at stud for a fee of 85,000 euros per covering.
The Aga Khan, who owns Zarkava, said last year: “In keeping with the motto of the Aga Khan Studs ‘success breeds success’ I look forward to the earliest opportunity to send my unbeaten champion Zarkava to Sea The Stars.
“I believe the last two Arc winners were made for each other both in terms of ability, temperament and conformation. The best needs to be bred to the best.”
Group One winners Lush Lashes and Alpine Rose have also tested as in foal to Sea The Stars over past few weeks.