McIlroy was forced to withdraw from next week’s Open after tearing ankle ligaments during a friendly game of football with his friends near his Northern Ireland home, and he has not yet indicated when he will be fit to return to action.
His absence increases the chances of Spieth landing his third straight major as he bids for a calendar grand slam, and McGinley warned the world No 1 that he still faces a bumpy ride throughout his career.
“Rory???s life from now until the end of his career is going to ebb and flow,” said last year’s victorious Ryder Cup captain. “There will be plenty of ups and downs, and this is obviously a down.
“Last year was a massive up. He won two majors and went back to the top of the world rankings with some big performances. But now he???s been really challenged by his nearest competitor Jordan Spieth winning the first two majors of this year, and now Rory is injured and missing the Open.
“This is a down, but that???s what is going to happen, in his life as well as his game. He???ll deal with this injury and come back with a point to prove.
“Rivalries in sport are what we live for, they bring us to the game of golf. We don???t want to see the same person winning week in, week out and running away from everybody ??? they need to be challenged, and Rory himself needs to be challenged.
“He???s certainly got that now with Jordan Spieth, but the sad thing is that Rory was so ready for the challenge of the Open, on his terms at St Andrews.”
Spieth is now the firm favourite to make it three consecutive majors at the Home of Golf next week, but McGinley feels that Louis Oosthuizen’s win in 2010 proves that an Open at the Old Course can produce a surprise champion.
He added: “Jordan won???t care that Rory is not in the field next week. The great thing about golf at the moment is the strength and depth is so strong. Louis Oosthuizen won the last Open to be played at St Andrews, and he started the week ranked outside the top 50 in the world.
“So there are a lot of players you can???t discount next week. Somebody ranked in the 40s or 50s is very unlikely to win Wimbledon for example, so it just shows you the difference in golf. As good as Rory and Spieth are, even as good as Tiger used to be, there???s still a huge amount of players capable of winning.
“The strength and depth in golf makes a major, in particular, a very difficult tournament to win. Jordan will understand that. He knows that, as well as he has been playing, there???s still 150-odd guys who are really good players and will be there to put up a proper, strong challenge.”
McGinley’s hopes of teeing up at St Andrews were ended by a missed cut at the Aberdeen Asset Management Scottish Open, but the Irishman was impressed with the course at Gullane and believes it was perfect preparation for those taking on the Old Course next week.
???I enjoyed the golf course, I thought it was very fair and there???s not a lot of undulation on the greens,” he said. “It???s a great examination for the guys getting ready for the Open.
???I think if you???re preparing for an Open Championship like these guys are for St Andrews, you don???t want to have a different test the week before. You want to get a feel for the links, you want to get used to the wind a little bit, the speed of the greens, the sands in the bunkers and hitting off the turf which is very different.
???You don???t want a very tough exam on top of all those other things and I think they???ve got it just right. Like everything on a links course, it???s all weather dependent, so it???s interesting to see over the weekend.???