AS Roma and Lazio played to a scoreless draw Sunday in a Roman derby featuring Serie A's two best defenses.
Roma remained in second place, while Lazio dropped to fourth, one spot behind AC Milan.
"We played well and at a fast pace. We just lacked a little luck, so we accept this draw with some regret," Roma coach Luciano Spalletti said.
Lazio had the better first half and Cristian Ledesma sent a searing shot just wide in the 34th minute at Stadio Olimpico.
In the 44th, Rodrigo Taddei missed a header for Roma with Lazio goalkeeper Angelo Peruzzi out of position.
Lazio midfielder Massimo Mutarelli was left unmarked in the 51st but volleyed wide.
Roma captain Francesco Totti played most of the match despite a back problem. He was replaced by Mirko Vucinic in the 73rd and Vucinic had the last chance of the match six minutes into injury time with a shot that Peruzzi handled easily.
After the match, Peruzzi announced he was retiring.
"That's it. I had already decided in January to retire after this season. Actually, this Roma-Lazio was my last game," Peruzzi told Italy's Sky TV. "I don't even think I'll play the next games. I've had three injections for a broken finger and I can't continue."
Lazio beat Roma 3-0 in December.
"They had more ball possession, but we had the better scoring chances," Lazio coach Delio Rossi said.
Inter Milan, which clinched the Serie A title last weekend, hosted Empoli later.
Inter leads with 84 points. Roma is next with 69 points, followed by Milan with 59 and Lazio with 58.
Palermo, which is fifth with 52 points, beat Livorno 2-1. David Di Michele scored the winning goal in the 75th minute.
Sampdoria won 2-0 at Siena with goals from Christian Maggio and Gennaro Delvecchio.
Gionatha Spinesi converted a penalty in the 53rd minute for Catania in a 1-0 win over Udinese, which had three men expelled in the second half. Udinese forward Vincenzo Iaquinta hit the post in the 26th.
Nicola Amoruso scored twice as Reggina won 3-2 at last-place Ascoli and Parma beat Cagliari 2-1 with a penalty in the 76th by Andrea Gasbarroni.
Also, Christian Vieri played well but missed several headers in Atalanta's 0-0 draw at Messina.
AC Milan warmed up for the second leg of the Champions League semifinals with a 1-0 win at Torino on Saturday.
Clarence Seedorf scored with a long, rising shot in the 26th.
On Wednesday, Milan hosts Manchester United in the Champions League. United won the opening leg 3-2.
Also Saturday, Fiorentina beat Chievo Verona 1-0 with a goal in the 64th by Reginaldo.