Pope Francis remained in critical condition Sunday and blood tests show early kidney failure but he remains alert and “well-oriented,” and attended Mass, the Vatican said, as the 88-year-old pontiff battles pneumonia and a complex lung infection.

Pope Francis, battling double pneumonia, remains in a critical condition and his prognosis is still guarded because of the "complexity" of his clinical condition, the Vatican said on Sunday.

The press office for the Vatican said Sunday that Pope Francis was able to rest overnight as he slowly recovers from double pneumonia after initially being hospitalized for bronchitis.