Archbishop Sean Brady has been described as a man of "humanity and integrity" ahead of the ceremony which will see him become a Cardinal.
Bishop Anthony Farquhar, the Auxiliary Bishop of Down and Connor, is also attending the Vatican ceremonies with Bishop Patrick Walsh and Auxiliary Bishop Donal McKeown this weekend.
Bishop Farquhar said: "All the good things that are being said about Archbishop Brady are true.
"He is a man of integrity and prayer, and I have never heard a bad word said about him. He is honest and straightforward, and will tell you what he thinks."
The two men first met in Rome in the early 1960s and were both members of the Irish College sports club, which featured basketball, soccer and gaelic sports.
Bishop Farquhar said: "Sean Brady was captain of the sports club.
"He was a good athlete and played basketball and a bit of soccer, but was a very good Gaelic footballer, which was his first love. He is a Cavan man and Gaelic football is very important in that part of the world.
"He was competitive on the sports field and he liked to win, but he always played and competed with integrity.
"He exercised a gentle but firm leadership as captain of the sports club."
Bishop Farquhar, who is President of the Irish Bishops' Conference on Ecumenism, has worked together closely with Dr Brady on ecumenical issues.
He said: "The Archbishop has been very committed in this area, and he has been most supportive to me personally.
"When we have staged major international ecumenical gatherings in Ireland, he has made a point of attending one or more of the sessions - sometimes at great personal cost in terms of time and travel.
"He is always keen to show his support for international delegates."
A large number of senior clergy from Ireland will be attending the Rome ceremonies this weekend, as well as Irish Government representatives and laity from all over Ireland.
Archbishop Brady will receive his Cardinal's red biretta from the Pope on Saturday morning at a ceremony in St Peter's Square, and on Sunday morning he will be given his Cardinal's ring.