For the first time in 22 years Pope John Paul II will "sit out" this evening's traditional Good Friday Via Crucis ceremony in the Roman Colosseum.
The Pope's medical team have forbidden him his normal practice of following the cross on its journey around the Colosseum and up the Palatine Hill.
The Pope will instead follow the ceremony kneeling on a special platform on the Palatine Hill, but he will still take an active part in the conclusion of the Via Crucis, carrying the cross for the 14th and final station before delivering his usual brief homily.
The Vatican's decision to limit the Pope's active participation in tonight's traditional Easter ceremony provides further painful indication of the increasing frailty of the 81-yearold pontiff.
Until this year the Pope has always followed the entire Via Crucis, in recent years carrying the cross for the first and last stations.
For some time now the Pope has all too clearly had difficulty in walking. The twin effects of Parkinson's disease and the right leg fracture suffered in 1994 mean that he is now all too visibly unsteady and slow on his feet.
For that reason he now uses a special mobile platform for major Vatican ceremonies while relying heavily on a walking stick on other occasions.
Despite the change in programme at tonight's ceremony, Vatican sources were this week adamant that the Pope's increasing physical frailty will have little effect on his busy spring and summer programme.
Yesterday he not only celebrated Holy Thursday Mass in St Peter's in the morning but also presided over the traditional Last Supper Mass at St John Lateran in the evening, during which he washed the feet of 12 priest-cum-disciples.
Vatican sources furthermore pointed out this week that the Pope still intends to make two important, potentially controversial and almost certainly exhausting overseas trips in the next two months.
From May 4th to 9th he will visit Greece, Syria and Malta in a trip which will not only focus on relations between the Roman Catholic and Greek Orthodox Churches but which will also feature a hugely symbolic moment when he visits the main mosque in Damascus.
From May 21st to 24th the Pope will chair a special consistory of cardinals in the Vatican, while from June 23rd to 27th he will visit Ukraine for one of the most controversial visits of his entire pontificate.
A reminder of the difficult nature of that trip came earlier this week when the Patriarch of Moscow, Alexis II, not only ruled out any forthcoming papal trip to Moscow but also called on the Catholic Church to stop its "proselytising" activities in Ukraine.
The Patriarch pointed out that the Pope had not been invited by the Ukraine Orthodox Patriarch Vladimir, adding that relations between the Vatican and the Orthodox churches could improve only when divisions between the Urkaine Orthodox Church and Greco-Catholics (Uniates), mainly over Uniate Church property confiscated by Stalin, were resolved.
Even the Pope's brief visit to Athens next month may not be without controversy, as indicated by a statement from the community of Orthodox monks on Mount Athos, near Salonika this week, which said: "The papal visit can only create problems and offers nothing in exchange to the Greek Orthodox Church."
Vatican sources confirmed this week that, notwithstanding potential controversy, both visits to Greece and Ukraine would go ahead.