The star, who was launched by Bhatt in 2002 hit 'Raaz', took to Twitter to express her joy over his surprise visit.
"First day of my new film Alone (tentative)! Good and productive. Day started with a surprise visitor @MaheshNBhatt! Was thrilled!" Bipasha tweeted.
The film is directed by Bhushan Patel, who has earlier helmed '1920: Evil Returns' and 'Ragini MMS 2' and marks the Bollywood debut of Grover.