Four of nine new coaches in the National Hockey League make their debuts tonight and three of the four new mentors in the World Hockey Association put their best skate forward in season openers.

The men behind the benches for the game in Pittsburgh are former NHL players - Leo Bolvin for the St. Louis Blues and Johnny Wilson for the Penguins.

Two of the other three NFL contests scheduled for opening night have Jean Guy Talbo at the helm of the New York Rangers against the Vancouver Canucks and Ron Steward masterminding the Los Angeles Kings against the Cleveland Barons.

Minnesota at Montreal is the other game.

Going into action Thursday night are the New York Islanders at Buffalo, which has Marcel Provonost as a new coach; Chicago, with incoming coach Bob Pulford, at Philadelphia; Bobby Kromm making his debut with Detroit against Toronto and newcomer Roger Neilson, and Atlanta at Boston.

Pat Kelly is the final newcomer. He brings Colorado up against Vancouver on Friday night.

Another double debut takes place in the WHA tongiht. Ron Ingram guides the Indianapolis Racers against Jacques Demers' Cincinnati S ingers and Larry Hillman has his first game as coach of the Winnipeg Jets against the Edmonton Oilers. New England at Houston rounds out the opening night schedule in the WHA.

The Birmingham Bulls and new coach Glen Sonmor hook up with Houston on Friday night.

The Montreal Canadiens are coming offf back-to-back Stanley Cup championship seasons and figure to again dominate the NL. With the exception of Jimmy Roberts, who went to St. Louis, the cam is intact and explosive, especially with scoring champion Guy Lafleur leading the attack.