Paulo Wanchope took over from Jorge Luis Pinto on an interim basis in the wake of Costa Rica's remarkable World Cup campaign, which saw them reach the last eight before being knocked out on penalties by Netherlands.
The former Derby County, West Ham and Manchester City striker made a successful start to his temporary tenure, guiding the side to Copa Centroamericana glory with a 2-1 win over Guatemala in the final last month.
Ahead of Friday's clash in Muscat, however, Wanchope was dealt a blow with the news that both Oviedo and Cubero will not be available.
Everton man Oviedo is having a small screw removed after he broke his left leg in an FA Cup clash with Stevenage in January.
Cubero, meanwhile, has picked up an ankle injury, and Johnny Acosta of Alajuelense has been called up as a replacement.
Despite those injuries, Wanchope is keen to keep building on Costa Rica's impressive World Cup showing.
"Our idea is to keep winning and playing well to maintain the good image that has been dragging from Brazil," Wanchope said.
"I think this is the right time to give young players the opportunity to be displayed. Within a year or two we have to make changes in some areas, hence the idea to provide the future coach a number of options to choose."
Wanchope's opposite number Paul Le Guen will be keen to return to winning ways after back-to-back defeats in friendlies last month.
Oman lost 2-0 to Republic of Ireland, before going down 1-0 to minnows Kosovo, who are yet to be recognised by FIFA.
In the aftermath of those two reverses, Le Guen bemoaned his players' lack of fitness, following a delayed start to the Oman Professional League.
With four rounds of action in the domestic season now completed, Oman's squad should be up to speed and looking to regain the form that saw them go 11 matches unbeaten before the defeat to Ireland in Dublin.
Oman conceded just one goal in those 11 outings, and will have to display all of their defensive qualities if they are to keep out the likes of Joel Campbell and Bryan Ruiz, who starred in Brazil.
