Gus

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The film opens in Yugoslavia with the Petrovic family watching their son Stepjan winning a soccer game. Their other son Andy works on his farm, and can't play soccer at all. One day, Andy discovers Gus can kick a soccer ball long distances when Andy shouts, "Oyage!". [Note: there is fierce debate in the Gus fan community re the spelling of "Oyage." Some spell it "Oyatch!," while others give it a more Yugoslavian-sounding "Ojigdz!"]
Meanwhile in Los Angeles, the California Atoms are a professional football team owned by Hank Cooper (Ed Asner) and coached by the inept Coach Venner (Don Knotts). They are the worst team in the league and have not won a game in years. Cooper also owes a lot of money to two mobster bookmakers named Charles Gwynn (Harold Gould) and Cal Wilson (Dick Van Patten). When Cooper tells them he cannot pay his debts, the bookies give him a last chance bet: if the Atoms win the upcoming Super Bowl, all gambling debts will be forgiven, but if they do not win, Gwynn and Wilson will take ownership of the team.
Desperate to draw in fans, Cooper looks for a great half time show. His secretary, Debbie (Louise 'Liberty' Williams), sees a story in her parents' Yugoslavian newspaper about Gus. Debbie flies to Yugoslavia and hires Gus and Andy. After Gus is a hit in his first halftime show, Cooper and Venner decide to put him in the game as a place kicker. The other team protests, but as the rule book does not require a player to be human, the referees allow Gus to kick. With Gus able to kick a field goal from anywhere in the field, the Atoms win. The Atoms go on to win their next few games thanks to Gus, and move to first place in their division. The only catch is that that Gus will only kick when Andy holds the ball and shouts the command. Debbie is assigned to watch over Andy and Gus, since she can speak Serbian. A romance begins between them, aided by Gus.
Gwynn and Wilson, realizing their deal with Cooper is backfiring, hire two incompetent criminals named Crankcase (Tim Conway) and Spinner (Tom Bosley) to stop Gus from playing. Through their schemes, Crankcase and Spinner cause the Atoms to lose two games. Despite the losses, the Atoms make the playoffs. Andy becomes a celebrity, but his parents remain unimpressed, saying he only holds the ball for Gus.
Before the playoff game, Spinner convinces Andy that Debbie has been injured in a car accident. When Andy arrives at the hospital, Spinner locks him up. Without Andy, Gus refuses to kick, and the Atoms fall behind. In the final quarter, Debbie dresses up in Andy's uniform and convinces Gus to kick a field goal, scoring the winning points. Andy, who managed to escape, arrives after the game is over. He tells Debbie his father is right: Andy is nothing, and anyone can hold the ball for Gus.
With the Atoms headed to the Super Bowl, Spinner and Crankcase steal Gus and replace him with an ordinary mule. Spinner and Crankcase check into a local hotel and lock up Gus with them. At the Super Bowl, Andy quickly realizes the mule he has is not Gus, and he and Cooper leave by helicopter to search for Gus. When the two criminals watch the game on TV, Gus goes wild and escapes. In a long comic sequence, Crankcase and Spinner chase Gus into a local supermarket where they unsuccessfully attempt to recapture the mule. Running from the supermarket, Gus is spotted from the air by Andy and Cooper. They airlift Gus to the Super Bowl and arrive by half-time.
With Gus back in the game, the Atoms make a come back. With 45 seconds left on the clock, the Atoms are down 16-15 with the ball on their own five yard line. Gus lines up for a field goal attempt, but slips in the mud and misses the football. In the scramble for the ball, Gus knocks it over to Andy, who runs 95 yards for the touchdown. As Andy and team walk off the field to celebrate their win, Debbie winks at Gus and says, "I know you did that on purpose". Gus winks back at her.

Question: Debbie is assigned to watch over Andy and Gus because she can speak what language?
Answer: Serbian