A single goal on Saturday was enough to widen Basel's lead at the top of the Swiss football league table.
The league leaders continued where they left off after last week's victory over Lugano with a 1-0 result at home to FC Zurich.
In their second match of the final round of the football championship, Basel waited until the 60th minute before Koumantarakis slammed the ball into the net to put the home side ahead.
In what turned out to be a lacklustre second half, Zurich failed to seize any chances of equalising and after 90 minutes were left to contemplate life at the other end of the league table.
Second-placed Grasshoppers Zurich fared better when faced with a visit from Bern's Young Boys.
In a closely fought match in front of 6000 fans, the visitors gave the home side a scare when Wardanjan put the Young Boys ahead in the 57th minute.
But Chapuisat responded with a magnificent goal of his own just 12 minutes later to draw the match level and leave his team seven points behind Basel in the league table.
In Sunday's other league ties, Servette will play Lugano, while St Gallen travel to Sion.
swissinfo with agencies
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