A woman is under arrest after jumping a barrier and lunging at Pope Benedict XVI at the start of Mass on Christmas Eve, in St Peter's Basilica in Rome.
The woman - who is said to be mentally unstable - jumped a security barrier as Benedict entered the basilica on Thursday.
The Pope, 82, appeared to be unhurt. The incident lasted only a few seconds.
The Pope was helped up by the master of ceremonies and quickly recovered his poise. However, he later stumbled several times in his homily.
Cardinal Roger Etchegaray, 87, of France was also knocked down. He is now in hospital with a broken leg.
Security officials detained the woman, who was later arrested.
During last year's Mass, a woman jumped the barriers and got close to the Pope, but was quickly restrained by security officials. It was not immediately known if it was the same woman.
The midnight service started two hours early because officials did not want the pontiff to get tired.
Pope Benedict earlier appeared briefly at nightfall at the window of his studio to light a candle in a sign of peace.