Roma's De Rossi delighted for shootout hero Diamanti
The Euros quarterfinal was decided on penalties.
De Rossi said: "I really like Diamanti, someone who played in the lower leagues and took a long time to reach the big stage, seeing him score the decisive penalties in the European quarter-finals was impressive.
"We did expect this sort of performance, as England have good players, but they do set out in a very defensive way.
"With the second chance I was sure that I wasn't offside, but I thought the goalkeeper was closer to me than he actually was, so I rushed the finish and didn't take time to control the ball first."