EDMONTON The final preparations are being completed for the 2023 Tim Hortons NHL Heritage Classic between the Edmonton Oilers and Calgary Flames at Commonwealth Stadium on Sunday, which is expected to attract a sellout crowd of 60, 000, according to NHL chief content officer Steve Mayer.Tickets are available for the first Battle of Alberta to be held outdoors 7 p.m. ET; TVAS, SN, TBS, MAX , but Mayer believes they will all be gone by puck drop.'We've been pacing really, really well and we have no doubt that by Sunday, that we're going to be completely sold out and there will not be a seat in this house, ' Mayer said at Commonwealth Stadium on Thursday. 'Anytime you come to one of these games and you realize there are 60, 000 people watching a hockey game, it's a pretty cool feeling. We realize there are a few seats available, so that if you're out there you can still come, but we also know that given where we are almost on every outdoor game at this time with four days left, we have no doubt we're going to be sold out for Sunday.'The Heritage Classic marks the 20th anniversary of the first NHL regular season outdoor game https://www.edmontonoilersstoreonline.com/connor-brown-jersey, played Nov. 22, 2003, when the Oilers hosted the Montreal Canadiens in the 2023 Heritage Classic at Commonwealth Stadium. The game started a trend that is going strong to this day.During his time in Edmonton, Mayer has met a number of fans who attended the 2003 game and sat in temperatures dipping to minus 22 with the wind chill to watch the Oilers Canadiens alumni game followed by the regular season game, a 4 3 Montreal win.'Three hundred thousand people were at that game, ' Mayer said jokingly. 'There is so much history when you look back, and the real reason we came here this year we had thought about this for a long time we always pointed to the fact 2003 was that first game and the 2023 game would be a 20th anniversary. So, we've been thinking about it for a while and the fact we're only a few days away to the big game is pretty cool. We're very much looking forward to this one.'  Dave Sandford NHLI via Getty ImagesThe rink is near completion https://www.edmontonoilersstoreonline.com/mattias-ekholm-jersey, and the teams are scheduled to practice on it Saturday night before squaring off Sunday in a game that has grown in significance. It will be the first matchup this season between the Pacific Division rivals, with each off to a slow start. Calgary is 2 5 1 entering Friday; Edmonton is 1 5 1.'Obviously, it's going to be a special day for us and for everyone involved, for the staff for the city of Edmonton and for the city of Calgary as well, ' Oilers forward Leon Draisaitl said. 'We're excited for it and it's going to be a special event to be a part of.'The Oilers' last outdoor game was the 2016 Heritage Classic at Investors Group Field in Winnipeg. The Oilers defeated the Winnipeg Jets 3 0 in front of 33, 240 fans. The Flames last played outdoors in the 2019 Heritage Classic at Mosaic Stadium in Regina, Saskatchewan, losing 2 1 in overtime to the Jets in front of 33, 518 fans.'It's a special event, and people are smart enough to know that you're not just going to another hockey game, ' Mayer said. 'It's an experience, it's a bucket list [item] for a sports fan. It's way more than just the game.From the opening introductions and the pyro and the flyovers and the fireworks and the music, there is something that we're going to activate on every single timeout. There's the wow' factor of being in a building with 60, 000 of your closest friends. There are certain things that we do that make it really special.'RELATED: More coverage of 2023 NHL Heritage ClassicThe 2023 Heritage Classic is the NHL's 38th regular season outdoor game and one of four scheduled for this season. The Seattle Kraken will host the Vegas Golden Knights in the 2024 Discover NHL Winter Classic on Jan. 1 at T Mobile Park, and the 2024 Navy Federal Credit Union NHL Stadium Series at MetLife Stadium in East Rutherford Xavier Bourgault Jersey, New Jersey, will feature the Philadelphia Flyers facing the New Jersey Devils on Feb. 17 and the New York Rangers taking on the New York Islanders on Feb. 18.'These games are memorable, ' Mayer said. 'We just did a repeat game in Boston last year 2023 Winter Classic at Fenway Park and we promised that it was going to be different, and we promise Sunday's game is going to be different if you came in 2003. It's a different experience and every time it's a little bit unique. Our goal is that anytime anybody goes to one of these outdoor games, it's something that they'll remember, especially if you're a fan of hockey, a fan of sports, a fan of events.'Mayer said the NHL will continue having outdoor games as long as the demand to host them remains high. He mentioned the need to be creative and referenced the NHL Outdoors at Lake Tahoe, the 2021 event that saw the League put a new twist on such games by staging two of them on a golf course amid a lake, trees and mountains.'We are starting to go to repeats. We are looking at what will make this series fresh and unique, ' Mayer said. 'There are still some stadiums that we haven't been to in North America. I do think that at some point we're going to explore a little of what we did in Lake Tahoe during the pandemic.'