The Liverpool defender limped out of Saturday's friendly in Bratislava after only 16 minutes and was then taken to hospital for scans.
But Skrtel has been told he needs only a few days' rest before he returns.
"It is not too bad, it is just a gash," Skrtel told the Slovakian Football Association's website. "I think that in a few days it will be okay."
And Skrtel was also encouraged by his team-mates' efforts as they brushed Costa Rica aside.
"I saw the second half," he added. "I think we will have delighted the fans. We wanted to win this match to put ourselves in a good place before the World Cup. We managed that.
"Perhaps the only negative is my injury, because to go off after quarter of an hour is not nice."
Skrtel suffered an injury-plagued season and was only making his second appearance since breaking a metatarsal in February.
Slovakia won thanks to an own goal from Douglas Esteban Solano Sequeira and further strikes from Robert Vittek and Stanislav Sestak after the break.