First, here are two short videos of David, holding what looks like a more or less improvised press conference for the Argentine press after the Nadal match...
Asked about some of the top players struggling at the moment, David mentions Djokovic and Murray having lost early at Miami and Federer losing at Indian Wells but says they're still far ahead of the other players, also in terms of the ranking.
He thinks he served really well against Nadal, much better than in his previous matches, so that's something very positive. As for the many unforced errors he made, he simply needs to train, play matches and spend more time on court. Playing his next match, the next tournament he'll still be lacking in terms of these things but it's just a question of playing and getting used to dealing with the pressure at 30-30 or 30-40, those moments you don't get in training.
He simply needs to play more matches. Though he played much better against Nadal than before. And he didn't feel any discomfort or pain, he felt quite normal. Of course he hopes the pain won't come back but there's no guarantee. He has only just started playing again and so far it's going well. Those muscular injuries he suffered were the result of not playing and being away from the Tour for so long. But though having surgery was a big thing his body has responded well.
Until Roland Garros and Wimbledon he'll have to be careful and listen to his doctors. But he's feeling much more calm now because they're telling him it's going better than expected and there were also no problems during his rehabilitation. So he cannot really say what the future will bring but he thinks he's on the right track.
He thinks he played well and that it was a good match. Though he obviously lost his rhythm after a set and a half and couldn't keep it up after that. But that's normal, as he still lacks match practice and simply hasn't played enough tennis yet.
Moving on to clay now, his plan is to play Monte Carlo, Barcelona, Rome and Madrid before Roland Garros. Using his protected ranking at Monte Carlo and Rome, while getting a wildcard for Barcelona. How he'll enter Madrid is apparently not completely clear yet* but he plans on playing it. He'll have to see how many matches he'll get on clay but he's optimistic.
(*Update - David is not on the entry list for Madrid with his protected ranking, so he'll apparently get a wildcard.)
There's also a new article about David on the tournament website for Barcelona, announcing his participation at this year's edition of the event and containing a couple of quotes. I've made their slightly dodgy English translation a bit more readable and closer to the original...
"Coming back is not about being inside the Top 100. I want to regain a place among the best."The same article claims that David has received a wildcard for Monte Carlo. Which is news to me and David also says something else in that clip above. The Monte Carlo website has David's name on the entry list both with his protected ranking and a star next to his name, signifying a wildcard entry. Though no wildcards have been announced yet... I think it might just be a mistake on the website.
"By the time I get to Barcelona I hope to be playing well. I know that it will be a difficult tournament for me, because the entry list is very impressive and there are a lot of clay court specialists. But I will give it my all and I want to please the fans, especially because there are always a lot of Argentinean supporters."
"This year, the clay court season will be even more special. I'm going to Europe, hoping to play well and to keep improving. I have no pressure, I'm just looking to find my game and gain rhythm, confidence and [ranking] points."
"At Indian Wells and Miami I've seen that I am injury-free now, and that I can relax and focus on improving my game. I want to compete, to feel good on the court again and enjoy it. I'm on the right track."
Finally, getting interviewed for Spanish Radio Marca, David once more talked about what might be called his favourite subject...
"It's a great competition and representing your country is something unique. I'm fortunate, being able to represent Argentina every time I play [Davis Cup] and it's a huge satisfaction. Winning the Davis Cup obviously isn't something that happens every day and hopefully, it's one of the titles I'll be able to win in my career."
Asked about a possible rematch against Spain, Nalbandian said that "it's still a long way to go" and that "Russia is a very difficult opponent."
"Right now, [the ranking] is secondary, it's not something I lose sleep over. I want to concentrate on my health and on feeling good again. I think that if I play at a good level, the way I did at Indian Wells and Miami, the ranking will take care of itself." (Source: Clarin)