A thumping right to the ribs had the Argentinian down in round two, before a well-timed right hook to the face dumped him on his back again in the next round.
The challenger seemed to have had enough and the referee duly counted him out.
"I knew he was going to be tricky because he was a name I wasn't familiar with, so I had to come out and be on form," Groves told Sky Sports News.
"I think I came out and did what Adam [Booth, his trainer] asked me. He will criticise me later but I thought it was a pretty good performance.
"I think I have got a world class jab, one of the best in the business and once I use that jab correctly, no one can live with me."
Groves's win means that his record has improved to 17 wins without defeat, including 13 knockouts.