Pope John Paul II has made a surprise appearance at the window of his Rome hospital to wave to people expecting his traditional Sunday blessing.
The Pope's appearance will reassure Catholics
Sitting in a wheelchair, the Pope made the sign of the cross to bless the faithful even though he did not speak.
In a message read out by an aide in St Peter's Square, the Pope asked believers "to continue to accompany me... with your prayers".
He has been in hospital since Thursday after surgery to ease his breathing.
This first appearance since the operation lasted about one minute but it will have done much to reassure Catholics around the world that the Pope is fighting back his illness, says the BBC's David Willey in Rome.
For the first time in his 26-year pontificate, the Pope delegated an aide to perform the Angelus blessing.
The doctors have told him he must not even attempt to speak.
The Pope has made a great effort to keep his appointment with the faithful every Sunday, appearing before them to give a blessing even when he has not been able to give his full address.
He managed to do so in 1981, after being wounded by a would-be assassin's bullet, and in 1992, after an operation to remove an intestinal tumour.
Some church officials and doctors have privately expressed doubts about the Pope's capacity to continue to exercise the office he has held for over 26 years.
Hour of pain
The Pope looked frail as he appeared at his 10th-floor suite at the Gemelli Hospital in Rome.
He waved to well-wishers and pointed to his throat where doctors inserted a tube during Thursday's tracheotomy operation.
THE POPE'S ILLNESS
1 Feb: Taken to hospital with "breathing difficulties brought on by flu"
6 Feb: Appears at hospital window and reads part of Angelus blessing in weak voice
9 Feb: Misses Ash Wednesday services at the Vatican
10 Feb: Returns to Vatican in motorcade, waving
13 Feb: Appears for Sunday blessing at Vatican
22 Feb: Launches book in which he compares abortion to the Holocaust
24 Feb: Returns to hospital following a relapse; has tracheotomy
The Pope's brief message to pilgrims gathered at the Vatican was read by Archbishop Leonardo Sandri.
In it he said "the current climate of penitence of Lent also helps us to better understand the suffering which one way or other concerns us all".
"Only looking to Christ and following him with patient trust shall we understand how all human form of pain includes a divine promise of salvation and happiness."
"I want this message of comfort and hope to reach everyone, especially those who are going through difficult times, who are suffering in body and soul."
The 84-year-old Pope spent 10 days at the hospital earlier this month with similar flu-related symptoms.
The Pope's doctors will shortly have to decide whether the tube must remain.
It is not known whether, or when, the Pope will be able to speak again.
At times in the past three years the Pope has had difficulty completing speeches and tires very quickly during public appearances.