“The mental aspect is so important for [Felix Potvin]. He’s got to get his first win to feel better about himself.”STEFAN LUNNER, Isles’ goalie coach

Islanders assistant Stefan Lunner is quick to say “I’m not Tommy Salo’s personal coach.”

Lunner, the first Swedish coach ever to be hired by an NHL team, adds, “I’m an Islanders assistant and goalie coach. I don’t care if the goalie is from Mars.”

And yet Lunner is scratching his head just like everyone else regarding the Jan. 9 swap of Bryan Berard-for-Felix Potvin, a move that pulled the rug from under Salo.

“If you asked me if I’m confused, the answer to that is, ‘Yes, I’m confused,'” Lunner told The Post yesterday. “I didn’t see the goaltending as the problem for this team.”

Well, there is a problem now – a huge, yawning one. Since Potvin came aboard, he has been absolutely dreadful. After allowing a touchdown to the Senators in two periods of work Saturday night in the 9-2 Ottawa scoring orgy, Potvin’s record moved to 0-5, his goals-against average ballooning to 4.47.

It doesn’t take a goaltending coach to tell you Salo has been better than Potvin since Jan. 9. Whether Salo remains a better goalie than Potvin the rest of his career is up for debate. But that uncertainty is why Jan. 9 stands for now as the darkest day in Mike Milbury’s Isles’ tenure.

“Yes, to me Tommy has looked more confident [than Felix],” said Lunner, who coached the Swedish National Team and has been Salo’s mentor. “But it’s not my call. I can put it this way: We have two good goalies now. But Tommy through the whole season has been consistent.”

Salo had made three straight starts, going 2-0-1 before new coach Bill Stewart turned to Potvin Saturday night. Potvin, in his first action in 11 days, looked uncomfortable. He is making tough saves but is letting in too many questionable goals.

“The mental aspect is so important for him,” Lunner said. “He’s got to get his first win to feel better about himself.”

Although he was under attack from the opening faceoff, Potvin allowed three goals in the opening 6:15 when he probably should have stopped two of them. That kind of spotty goaltending takes the life out of a club and the Isles were drowning the rest of the humiliating night. The superbly speedy Senators, who are emerging as a league power, had the bloodthirsty Corel Centre crowd chanting “We want 10” in the third period.

On the game’s first goal, Potvin failed to cut down the angle on a Shawn McEachern shot from a difficult spot at the outer edge of the left circle.

“A goalie’s got to be there for that,” Lunner said.

Lunner said he is working with Potvin on coming further out of the net to cut down angles and to face up more boldly against the shooter. “He’s a very good goalie, you see it in his technique, he’s tremendously fast with the glove,” said Lunner. “He’s made a lot of good saves but you have to stop the green-sector shots.”

That’s Lunner terminology for shots which either arrive from bad angles or shots in which the goalie has clear vision. Salo has reduced the amount of soft goals this season. Consequently, the Isles seem to play with more energy in front of the Swedish netminder.

‘It’s a combination,” Lunner said. “The team has helped Tommy and Tommy has helped the team be successful.”

Stewart seemed to be grasping for straws when defending Potvin after Saturday night’s game. Stewart said Potvin has gone through a “traumatic” experience because this was his first trade. Please. Potvin had all but begged to be traded from Curtis Joseph’s Leafs.

Stewart is just being the good soldier, not wanting to be critical of the trade. But it’s been learned from a team source that Stewart had his eyebrows raised, too, on the day of the Potvin deal. That isn’t surprising, considering Stewart had become one of Berard’s staunchest supporters as an assistant who worked with the defense.

Milbury has kept away from the team since firing himself as head coach 11 days ago and has been unavailable for comment. Today, Milbury flies to the GM meetings in La Quinta, Calif., perhaps wondering which goalie he should try to peddle. end of story