|ESPNsoccernet: World Cup 2010|
Marcello Lippi said he was deeply unsatisfied after Italy's 1-1 draw against Paraguay.
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Italy struggled to create chances in the first half and were left shocked when Antolin Alcaraz headed home a free-kick in the 39th minute.
The defending world champions did improve in the second half, though, and Daniele De Rossi equalised on 63 minutes, yet Lippi feels his players should have gone on to win the game.
"There is a great regret, as we certainly deserved to win the game," he said on Football Italia. "Paraguay scored with their first approach on goal, which can happen from a set play.
"There was a reaction and we played a good game, but this is the kind of match we have got to win, so we need to improve in attack. Paraguay preferred to sit back and defend, creating absolutely nothing."
De Rossi, meanwhile, accepted responsibility for the goal as he failed to track Alcaraz.
"We played well, were tough and allowed Paraguay very little," he said. "My mistake led to the goal, so everyone was angry.
"We were going too deep defending the free-kicks, but he was my man and I was meant to be marking him. I definitely take the blame for that goal."
He added: "We passed the ball around, but were a little sterile in the final third and you pay for that at this level. We need to improve in the final third, to be more clinical and to get the final pass into the box. That's what counts in a World Cup."
De Rossi believes Italy are still contenders this year even if they are not the favourites.
"It's never easy to evaluate on the basis of the first game," he said. "We are not so arrogant as to assume we are better than the rest.
"There are two or three sides with better quality throughout, namely Spain, Argentina and Brazil. England are more similar to us, but we are always tough for any opponent. Let's not forget we only lost to Spain on penalties in Euro 2008."
Paraguay boss Gerardo Martino felt it was a good result but said the injury to substitute Jonathan Santana had hurt his team.
"We were well organised and defended very well in the second half, but then Santana was injured," he said. "I think it's a positive result, given who we were playing. It was our first game, and there was so much expectation, but the game should help us to think about how we can improve."