De Boer, who played for Rangers from 2000 to 2004, was impressed with Mark Warburton’s side’s performance against Celtic last month.
The Gers got the better of Old Firm rivals Celtic on penalties in the semi-finals of the Scottish Cup at Hampden Park in Glasgow in April. The match finished 2-2 after extra time, and Rangers clinched the penalty shootout 5-4.
Rangers were the better team on the day, and their passing football was entertaining to watch.
De Boer, a former Netherlands international who could play as an attacking midfielder or as a forward, was impressed with his former club’s display. The former Barcelona star has also praised Rangers for playing football the modern way.
“If you really want to have success, particularly in Europe, then you have to play this ‘modern game’,” De Boer told Rangers’ official website.
“What I saw against Celtic was the ‘modern game’ – and it’s also so much about people running off the ball, not only on the ball.”
The Gers, who have also clinched the Scottish Challenge Cup, will take on Hibernian in the final of the Scottish Cup at Hampden Park in Glasgow this coming weekend.