Part-timer Matija Pecotic had to put a request in for another day off work to play in the second round of the Delray Beach Open after pulling off a shock win over Jack Sock.

The Croatian came through qualifying to make his ATP Tour main-draw debut in Florida and the 33-year-old is through to the last 16 after a 4-6 6-2 6-2 victory against former world number eight Sock on Tuesday.

World number 784 Pecotic has a full-time job in finance and he will be in the money after setting up a meeting with Marcos Giron in the last 16 of the ATP 250 event.

The Princeton and Harvard graduate's boss was in his box to watch him see off Sock and Pecotic hopes he will get a chance to book a quarter-final spot on Wednesday rather than return to balancing the books.

He quipped: "I had to leave work early today. I had to send an email to the whole team. [My boss] let me off. I'm going to have to ask for another day off tomorrow."

Pecotic, who served 10 aces and struck 30 winners, added: "I certainly didn't expect to win, but certainly didn't come into the match thinking that I'm definitely going to lose.

"You've got to be realistic. This is a former top 10 guy with an incredible amount of tennis experience, with a huge serve.

"He came out serving 134 [mph] on the first serve. It would be arrogant to think that I'm going to come out and expect to win.

"But I certainly figured if I could sink my teeth into the match and work on the two or three patterns that I prepared before, that I'm going to have a chance. And then let's see... if I was going to fall under pressure or not be able to serve it out at some point. But I didn't and I got the win."