Watford defender Francisco Sierralta will undergo a scan on his right calf after missing Chile's Copa America opener against Argentina.

The centre-back was expected to start the match last night, which ended 1-1, but was left out of the squad due to the injury.

The extent of the problem will now be assessed before his involvement in the remainder of the tournament can be judged.

Spanish Publication AS have reported: "The Watford footballer was going to be Gary Medel's companion in the Reds' defence.

"A physical problem left the defender out of the Copa América debut. He has a muscle injury in the right calf. Tomorrow an imaging study will be carried out."

The news comes the day before Watford's Premier League fixtures are to be announced.

Sierralta is expected to have an important part to play in the Hornets' upcoming season after impressing during their Championship promotion campaign.

Chile's next match at the Copa America is on Friday night against Bolivia, at 10pm BST.

After that, they face Uruguay in their final group match on Monday.