WWE Superstar Sheamus missed two shows last week in Australia and it appears as though a head injury could be the cause.

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Sheamus was booked to battle his current rival Randy Orton at house shows in Brisbane and Melbourne, Australia, but he was replaced by Bad News Barrett and didn't appear at all.

The Celtic Warrior has either been diagnosed with a concussion or the WWE is taking a precaution assuming he has one, Wrestlingheadlines.com reports.

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There is a belief that Sheamus suffered a head injury on Monday Night RAW last week during the six-man main event that pitted him, Bray Wyatt and Luke Harper against Orton, Roman Reigns and Dean Ambrose.

There have been no reports as to at what exact point the head injury was sustained, but there is a lot of speculation that Sheamus is dealing with a concussion.

The WWE's Irish Superstar took to Twitter to address the rumors that have cropped up and even admitted that he is nursing an injury:

The WWE had planned for Sheamus and Orton's rivalry to carry over into the huge SummerSlam event in less than two weeks at the Barclays Center in Brooklyn on Aug. 23.

It's uncertain how serious the ailment is, but there is a possibility it could sideline him for The Biggest Party of the Summer if it turns out to be a concussion due to the WWE's policy on head injuries.

Sheamus is also a prominent figure in the WWE because he has the Money in the Bank briefcase, which guarantees him a WWE World Heavyweight Championship shot anytime between now and June.

It's unknown at this time if The Celtic Warrior will appear on RAW this week.

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