FLORHAM PARK – Rex Ryan’s one-liners weren’t as plentiful as usual Monday and there also was a shortage of his normal quota of knowing smiles. Ryan has some weighty issues on his mind this week, as the Jets prepare to face Dallas in the regular-season opener on the 10th anniversary of the infamous Sept. 11 attacks. The Cowboys’ new defensive coordinator is Rex’s twin brother, Rob, and their father, Buddy, is delaying an operation so he can attend the game. Buddy Ryan, who previously has beaten melanoma twice, has cancer in the carotid gland in his neck. “Usually, it’s [about going] against my brother and all that,” Rex Ryan said, “and you have a lot of fun with that, but obviously I feel [this week] it’s different, like a responsibility. … I don’t know, it just feels different to me. The significance of it, I think it’s stronger than any game I’ve ever felt. I feel more pressure on this game for whatever reason than any game I’ve ever coached, it seems like.” Ryan recalled being at the Baltimore Ravens’ facility on that awful morning 10 years ago, walking by the office of a team executive, Pat Moriarty, and noticing the horrible scene of devastation unfolding on television. “I’m watching it,” Ryan said, “and right when I was watching, the other plane hit the second tower. I was like, ‘Oh my goodness.’ ” Ryan was asked if he felt a responsibility to win this game for the New York/New Jersey region. “I think maybe that’s it,” he said, agreeing. “I know it’s football and we’re not talking about life or death or anything like that, but I don’t know, that’s kind of how I’m taking it. It’s my job.” The Jets visited the almost-rebuilt Ground Zero site last Wednesday after their annual charity luncheon. “It was special,” veteran running back LaDainian Tomlinson said, “because I think for a guy like me who was on the West Coast at the time, I really didn’t get a chance to see it up close. “When you go there, there’s a certain aura that you have when you stand there and you just imagine that day and just the chaos and everything that so many families and people went through. It just gave you that feeling that you’re special. You’re lucky to be standing on that spot but at the same time you’re special because you get a chance to do something that a lot of people don’t get to do. But it’s very humbling at the same time.” Ryan also will be thinking about his father. Buddy Ryan told the Associated Press in a telephone interview that he will postpone an operation for the cancer for a few days so he can fly in from his home in Kentucky on Friday for the game, and then fly back Monday. The doctors “said to go ahead and go,” Buddy Ryan said. “I’ve got to be able to do something” while waiting for the operation. “It’s going to be great to have him here,” Rex Ryan said. “I know this is huge for him. He’s looked forward to it for a long time.” He added that he certainly is worried about his father’s health. “Anytime you have cancer again, there is a huge concern,” Rex said. “Obviously, [we’re] praying a lot for him and things have to go well because that’s what it is,” Rob Ryan told reporters Monday. “But he raised us to do the job.” No matter what distractions there might be. “My job is to get this team ready to go,” Rex Ryan said. “And we will” be ready. E-mail: