The big day arrives Saturday, when Montreal will face east-leading Sporting and Arnaud will appear in Kansas City as a visiting player for the first time in his 11-year career.
"It's going to be a different feeling the whole weekend," the midfielder said. "Going to Kansas City and staying at a hotel. Pulling into the stadium in a bus instead of driving there. Going into the other locker-room. I'm going to see it from the other side. I saw it from the home side for a long time, so it'll be different."
Arnaud was drafted by Kansas City, then called the Wizards, in 2002 and spent his entire career there until he was traded to Montreal on Nov. 28 for Seth Sinovic, a defender who had been taken from Sporting in the expansion draft.
The midfielder had been captain in Kansas City since 2010, and now wears the armband in Montreal, but was deemed expendable after struggling with injuries last season.
He sold his house there during the pre-season and now feels that "once you leave and go to a different city, you've moved on," but he still considers it a special place to play.
He brings with him a 2-5-2 club that is coming off a 2-0 victory at home over the Portland Timbers and a 0-0 draw in Amway Canadian Championship play against Toronto FC.
They are up against one of the league's hottest teams at 7-1-0, although Sporting's last outing was a 1-0 loss on an own goal in Portland. They are 4-0 at home.
Arnaud knows what to expect from a team whose top striker Kei Kamara is averaging eight shots per game.
"They're going to have a ton of energy and they're going to come out really hard," he said. "The tempo of the game is going to be very high, especially coming off a bye week, so they've had a lot of rest. We'll have to be ready to match that. It won't be easy for us. It's a tough place to play. But we have to be prepared for that."
How much fight the Impact will give them is a question mark.
In the midst of five games in a 15-day span, coach Jesse Marsch said he would make several lineup changes, including giving defenders Nelson Rivas and Hassoun Camara their first action of the season. Midfielder Patrice Bernier is also to play after riding the bench for most of the past month.
Marsch said all his players know the system of play and should be ready to perform, even if it may look like the newcomers are being thrown to the lions.
"We still feel we'll put a very good team on the field and go for a result," said Marsch, whose club is seeking its first away victory. "If you haven't been to Kansas City, it's a beautiful stadium, a great environment and a very good team.
"It'll be a really good test for our team and it will also be fun for our team to go there and play. You go to different cities and get the feel of what the league's about. But I expect us to go there and get a result."
Kansas City played its first 10 games of the 2011 season on the road as their new stadium, Livestrong Sporting Park, was completed. They had only one win in that stretch, but then turned their season around to finish first in the east.
The winning has carried into the current campaign.
"You saw once the road trip ended last year they made a great run," said Arnaud. "It's a very good team and I'm not surprised by their start."
Sporting has scored 12 goals and allowed only three in eight games. They are especially dangerous on set pieces. It should be a test for the new faces on the Montreal defence.
Even Arnaud will feel a little out of place. He said he has only been in the visiting locker-room there once.
"It was during a game," he said. "I had to go to the bathroom and it was the closest one, so I snuck in there. It's not as nice as the home team locker-room."
Sinovic will miss the game with a hand injury.
Montreal is without right back Zarek Valentin (bruised right calf) and midfielder Justin Mapp (hamstring).