The chair behind his desk is certainly plush, and Jim Fassel can crack a smile when asked about its temperature. Yes, those three dirty little words that often add up to the end of the line for coaches have invaded his very office, his personal space. Fassel has, reluctantly, become familiarized with The Hot Seat.

It is from that uncomfortable vantage point Fassel will guide the Giants into what could be his final training camp. Rookies are set to report tonight to the University at Albany, with veterans arriving tomorrow and the first practice coming Saturday morning. Fassel, in desperate need of a winning season, realizes a popular theme this summer and fall will be the make-or-break nature of his existence. Win, you stay. Lose, and management eats the final year of your contract, thanks you for your efforts, sends you on your way and searches for a successor.

Under the heat of the sun, Fassel will immediately face not curves nor changeups, but straight fastballs. So, Jim, what’s it like coaching for your job?

“From my standpoint, I’m going to answer that question and then that’s it,” Fassel said recently in an interview with The Post. “I’m not going to talk about it. It’s not going to become an issue. That’s not the foremost thing on my mind, so if it’s not at the top of my mind, I’m just not going to keep talking about it.”

Fassel likes to remind anyone who will listen that exactly a year ago, the NFL coach considered first in line to be fired was his good friend Dick Vermeil. Who knew Vermeil was sitting on a powderkeg of a team that would explode its way to a Super Bowl triumph?

If Vermeil could defy the odds and rise out of The Hot Seat, Fassel sees no reason why he cannot make the same ascension.

“As a coach, when you start in coaching, chapter one, if you’re afraid for your job – ever – don’t get into this profession,” Fassel said firmly. “Every year they’re going to say, ‘Well, if he doesn’t do this, this year, they might let him go.’ “

They will let Fassel go if the Giants continue to falter. The downward trend in Fassel’s three seasons (from 10-5-1 to 8-8 to last year’s 7-9) has alarmed the front office. Fassel looked like a goner when the Giants lost three straight last season to fall to 5-6, but he saved his job with rousing victories over the Jets and Bills. A depleted, injury-riddled roster cost Fassel any shot at a fast finish, and three consecutive losses to close out the season gave Fassel no margin for error in 2000.

Entering the final year of his original four-year, $3.2 million deal, Fassel wanted a three-year extension but the Giants stood firm with a one-year offer. On Jan. 27, Fassel agreed to the additional year (for $1.2 million) as well as a raise from $825,000 to $1.1 million for this coming season.

The message was clear. The Giants did not want Fassel to be a lame-duck coach in 2000, but they in effect were offering him a nice severance package if he could not turn the team around this season.

Fassel said at no time did he ever believe he was close to getting fired. He says he has no problem with the one-year extension, but understands the ramifications if he does not deliver a winning team.

“I didn’t ride the wave last year that everybody did,” Fassel said. “After we beat the Jets and Buffalo all everybody was writing was ‘new four-year deal’ and all this money. That never fazed me. I don’t ride those waves. If I did, this job would be too stressful. There were things said, that the negotiations were not amicable, that there were a lot of demands made. Absolutely none of that was true. I feel we reached a very fair agreement. Very fair to the Giants, very fair to me.

“The clear messages were, ‘We like you, we want you to be our coach, we want to get going on the right track, we hope we’re doing this again next year. But yeah, we got to win.’ “

From the outside looking in, the overwhelming feeling is Fassel won’t survive, as the Giants are lightly regarded around the league, expectations are extremely low. Fassel and management believe the Giants are being overlooked. Clearly, Fassel is more confident in his quarterback, Kerry Collins, than any of Collins’ pretender predecessors, and just as clearly, Fassel believes the talent has been upgraded. “We got some thin spots, some spots that kind of make me nervous,” he said, “but arguably we’ll take the best team in.”