The German popped up eight minutes from the end to net his tenth goal of the season and his first in a Lazio shirt against the Nerazzurri. The visitors struck the woodwork twice, but ultimately failed to make up ground on league leaders Juventus as Lazio won 1-0.
Klose returned to spearhead the Eagles attack and Abdoulay Konko also shook off a knock to start. Senad Lulic was preferred to Antonio Candreva, while Ederson joined suspended duo Luis Cavanda and Libor Kozak on the sidelines. Mauro Zarate reportedly stormed off and left the stadium upon learning he was a substitute.
The visitors initially set their stall out to frustrate Lazio and contain their danger man Hernanes. Both Javier Zanetti and Esteban Cambiasso marshalled the Brazilian throughout the first half and restricted him to a couple of tame long range efforts.
Just after the half hour mark, Michael Ciani deflected a Guarin shot wide. From Cassano's resulting corner, Ranocchia headed over.
Nine minutes before the break, Konko put the ball into the danger area. Both Klose and Hernanes snatched at it, but Yuto Nagatomo's crucial block snuffed out the chance.
Lulic went on a mazy run, before combining with Hernanes to release Stefano Mauri. Samuel prevented the Lazio midfielder from getting a clear shot off. The resulting corner hit the heads of both Klose and Giuseppe Biava to go wide.
Three minutes before the break, Klose was furious at being refused a penalty. The German was anticipating a deep Mauri cross when Alvaro Pereira seemed to clip his heels in the penalty area. Neither of the three officials saw anything from their angle and play continued. The frontman received the ball in the area in stoppage time, but ran into Inter traffic.
Pereira's dangerous ball was acrobatically punched clear by Marchetti before Milito could get his head on it, as Inter began the second half on the front foot.
Mauri rolled the ball across and managed to find Hernanes in space, but the playmaker disappointingly curled over. At the other end, Guarin squeezed a shot past four Lazio players, but also just wide of the post.
Cambiasso limped off, forcing Andrea Stramaccioni to re-shuffle his pack. Miscommunication between Stefan Radu and Marchetti almost led to an own goal. No visiting players were around as the pair hesitated in putting a wayward long pass out of play.
The Nerazzurri continued to assert their authority halfway through the second period. Guarin bent a low shot past Marchetti, only to see it come back off the post. Milito quickly ran onto a through ball and shot wide.
On 71 minutes, Hernanes stung Handanovic's palms after bending a free-kick over a three man wall.
A minute later, Marchetti had to pull off a fantastic double stop to deny Inter. After pushing Cassano's shot onto the post with his fingertips, the shotstopper quickly jumped up to deny Nagatomo. The danger still wasn't clear as substitute Rodrigo Palacio curled his shot the wrong side of the post.
Klose miscontrolled right in front of goal, then fluffed a chance after going on a mazy run. The third time proved to be a charm as Klose gave Lazio the lead against the run of play. Mauri's through ball found the veteran, and despite being marshalled by two Inter players, managed to sweep the ball past Handanovic. Klose seemed to re-aggravate a previous injury and was quickly substituted.
Inter threw on Philippe Coutinho and the substitute nearly made an instant reaction, getting on the end of a free-kick and blazing over. Inter pushed forwards, but could find no way past the Lazio backline.
Lazio: Marchetti; Konko, Biava, Ciani, Radu; Ledesma; Lulic (Candreva 64), Hernanes (Dias 87), Gonzalez, Mauri; Klose (Floccari 85)
Inter: Handanovic; Nagatomo, Ranocchia, Samuel, Pereira (Coutinho 86); Zanetti, Gargano, Cambiasso (Palacio 60); Guarin; Milito, Cassano
Goal: Klose 82 (L)