The two men finished bottom in the public vote. For Dirk, it was the second night in a row he found himself singing for his survival.
The pair sang a duet of Christina Aguilera's 'Hurt', before going over to Andrew Lloyd Webber for the final decision.
Lloyd Webber chose to save Tim, arguing later that he felt the 32-year-old had more connection with the material.
After being voted off, Dirk thanked the musical impresario for giving him the opportunity, saying working with him had led him to develop hugely as a singer.
When host Amanda Holden asked Tim how the sing-off affected him, he replied: "That was the toughest thing I've ever had to sing."
When she asked whether he would be able to regain his composure for the rest of the show, he joked: "I'll go and do some chin-ups or something."
Watch the Superstar contestants tell Digital Spy about their most embarrassing moments below: