Lazio goalkeeper Fernando Muslera allowed Marco Borriello's weak penalty to creep under his body as city rivals Roma won the Rome derby by beating the Serie A leaders 2-0 yesterday.
Mirko Vucinic added another second-half spot kick late on to secure victory.
Lazio's first league defeat since the opening day meant second-placed AC Milan cut the gap to two points and leapfrogged champions Inter with a 3-2 win at bottom side Bari. Massimo Ambrosini, Mathieu Flamini and Alexandre Pato were on target for Milan, with Vitali Kutuzov and Paulo Barreto replying.
Juventus came from behind to beat 10-man Cesena 3-1 with Alessandro Del Piero (penalty), Fabio Quagliarella and Vincenzo Iaquinta on the scoresheet.
Edinson Cavani's double gave Napoli a 2-0 win over struggling Parma while sixth-placed Sampdoria could only draw 0-0 with Catania.
In Spain, Lionel Messi, David Villa and Pedro gave Barcelona a 3-1 win at Getafe. However, the victory was marred by a sending-off for defender Gerard Pique and Manu del Moral pulled one back for Getafe from the penalty spot shortly afterwards.
Villarreal came back to beat Athletic Bilbao 4-1. Fernando Llorente headed home after only six minutes at the Madrigal, but Villarreal turned the game around before the break. Brazilian Nilmar levelled with a header in the 39th and Santi Cazorla capitalised on a poor clearance to net six minutes later. Bilbao had defender Jon Aurtenetxe sent off in the 77th for a second bookable offence, and Giuseppe Rossi and Jefferson Montero scored breakaway goals at the end.
Borussia Dortmund extended their lead at the top of the Bundesliga to four points by winning 4-0 at 10-man Hannover after second-placed Mainz 05 slumped to a 1-0 defeat at Freiburg on Saturday.
Shinji Kawaga gave Dortmund the lead in the 11th minute but it was not until the 72nd minute that Lucas Barrios added the second. Hannover's Karim Haggui was sent off in the 77th minute and although Dortmund's Nuri Sahin failed to convert the ensuing penalty, Robert Lewandowski and Jakub Blasczcykowski added further goals.
Bayer Leverkusen are third after coming from a goal down to beat Kaiserslautern 3-1 while VfB Stuttgart climbed out of the drop zone with a 6-0 romp against Werder Bremen.