Problem: Article: The Argentina Football Association confirmed the 28-year-old picked up the injury during City's 3-1 Premier League win over West Ham on Sunday.
No timescale has been given for his return, with Aguero potentially facing FA charges for elbowing Hammers defender Winston Reid.
Argentina play Uruguay on Friday, before facing Venezuela on 7 September.
Lionel Messi has also been training with Argentina after reversing his retirement decision, which was made at the start of August.
However, the 29-year-old Barcelona man has suffered a hamstring injury ahead of travelling to South America and whether he plays "will depend on how the injury develops", according to his club.
Argentina are currently third in the qualifying table after winning three of their six games.
Answer: [[Manchester City striker Sergio Aguero has been ruled out of Argentina's World Cup 2018 qualifiers with a calf injury.]]

Problem: Article: Powys council has launched a review and is looking at closing sites serving areas with lower populations, such as Machynlleth.
The authority said the site in the town was under threat but it would consult the community before making a decision.
But the plans have been criticised by the area's local regeneration organisation Ecodyfi.
Ecodyfil manager Andy Rowland said closing the recycling centre in Machynlleth would be a "backwards step" and the site was the only one of its type for "miles around".
Asked what sort of impact the centre's closure would have on Machynlleth, he said: "I think it will be disastrous.
"It serves the Powys part of the Dyfi Valley and the section in Gwynedd. It's really well-used and appreciated and the only one for miles around."
Powys council has six centres around the county but it said the review was due to the "ever increasing financial pressures facing the council".
The nearest of the five other centres is in Newtown 29 miles away, while the next nearest is in Welshpool, 37 miles from Machynlleth.
The council's deputy leader Rosemarie Harris said the cost of providing the service continued to rise due to changes in waste legislation, increasing landfill costs including landfill tax, increasing processing costs for recycling as well as the operational cost of providing it.
She added: "This is not something that has been taken lightly by the cabinet but we are facing tough financial pressures and we are unable to continue with our existing arrangements."
The council said there were a number of alternatives in place to fill the gap if the recycling centre shut, including a new kerbside recycling scheme.
Answer: [[Plans to shut a town recycling centre in Powys have been branded "disastrous".]]

Problem: Article: "I don't want to live like that," the Gangnam Style singer confesses.
"I am not that responsible person. I hate the word responsibility. I wasn't responsible at all before Gangnam Style and now I gotta be good."
Psy, 34, says he was "bad ass" before the worldwide success of Gangnam Style.
The video has now been viewed more than 700 million times on YouTube.
In previous concerts, Psy has dressed in revealing PVC outfits and covered Lady Gaga songs.
In 2011 he performed Beyonce's Single Ladies on stage wearing a leotard.
Earlier this month Psy was awarded the Okgwan Order of Cultural Merit by South Korea's Culture Ministry, for increasing awareness of South Korean pop music and interest in South Korea.
When asked how he felt about being used politically, Psy admitted he was "not that kind of person".
He also recounted a tale of being photographed in Toronto recently standing by a no smoking sign which did not go down well at home.
"There was a public ashtray there," Psy protested. "That's why I smoked there and everybody smokes there so I thought it was all right.
"But in Korea that was kind of a bit of trouble so people say, 'Oh Psy, you are representing our country so don't do that.'
"That kind of thing happens these days."
At the weekend Psy won best video for Gangnam Style at the MTV Europe Music Awards and he says he is working on his first international album.
That will be recorded half in English, half in Korean and will be released in 2013.
Answer: [[South Korean singer Psy says he's unhappy with the "heavy pressure" of representing his country on a global scale.]]

Problem: Article: It is the third time that the 22-year-old, who was released by Yeovil at the end of last season, has signed for the Shrimpers after two spells in 2014.
"The short-term deal we've put him on will hopefully keep him focused on the field of play so we get the Jakub of old," boss Phil Brown said.
"If we get the Jakub of old, he's one of the best in the league."
Find all the latest football transfers on our dedicated page.
Answer:
[[Southend United have signed former Yeovil Town centre-back Jakub Sokolik on a five-month contract.]]