Former Scotland and Rangers manager Walter Smith is recovering in hospital after undergoing an operation, the Scottish champions confirmed in a statement on Saturday.
No further details have been released about the condition of the 73-year-old, who also had a spell in charge of Everton.
Rangers said in a statement: "Rangers Football Club can confirm Walter Smith had an operation on Monday and he is currently recovering in hospital.
"His family have requested privacy at this time."
Already at Rangers as assistant to Graeme Souness, Smith was appointed full-time manager at Ibrox in 1991 and won six league titles in seven years during his first spell in charge.
After a four-year stint at Everton and a brief spell as Alex Ferguson's assistant at Manchester United in 2004, Smith was appointed manager of Scotland in 2004.
In 2007, he returned to Ibrox, winning three more league titles and guiding Rangers to the UEFA Cup final in 2008 before retiring in 2011.
His two spells in charge of Rangers saw him win 21 trophies, becoming the Glasgow giants' second-most successful manager behind Bill Struth.