Winning the North American Soccer League spring season championship means Minnesota United FC knows the playoffs are assured.

The payoff is less certain.

United’s 7 p.m. match Saturday against Tampa Bay is one of five the Loons have left at the National Sports Center Stadium in Blaine.

And the fight for relevance is on. The World Cup and three local “summer of soccer” international matches have passed. Kids are back in school. The NFL is in full swing.

Team president Nick Rogers said an attendance “drop-off” occurred “last year around this time.” But he hopes benefits will accrue from a season-long investment in high-level soccer.

Owner Bill McGuire, who rose to prominence nationally as the head of Minnetonka-based UnitedHealth Group for more than 15 years, financed preseason training in California and England. Those trips helped the team start fast and, in securing the title, grab one of the top two seeds in November’s four-team playoff.

Brand awareness increased through locally televised home matches all season. And players have done their part, making the Loons league-leaders with 17 victories and 33 goals overall.

As a result, paid attendance has doubled from the 2013 season. Total attendance is 91,298 so far this season compared to 62,030 in 2013. Average attendance is up 36 percent for games at the National Sports Center, from 4,658 to 6,361.

Sponsorship dollars have increased “tenfold,” Rogers said, though he would not disclose a dollar figure. New sponsors this season include Mall of America, Explore Minnesota and Atomic Data.

“No matter what, it’s already been a hugely successful year,” Rogers said.

Doubling marketing expenses, Rogers said, helped spread the word. But on-field success made the biggest difference. A year ago the team managed a combined record of 10-12-4. Now one of the league’s top teams, United saw its 11-match unbeaten streak end last week at Edmonton. The Loons remain second in the fall season standings.

Two weeks ago, after an uninspired draw at New York, fans took out their frustrations in posts on Twitter. Forward Miguel Ibarra responded with a tweet reminding fans the team still earned a point for the tie.

“Our fans are really passionate and that just motivates us more,” Ibarra said.

Forward Jamie Watson said: “We’re now at a point where the standard is so high that when you don’t win you have questions to answer. Expectations are probably the highest they’ve ever been. We’ve earned that.”

Rogers said that while he doesn’t expect home crowds to “fill the building’’ for matches Saturday or next Saturday, the team has already sold more tickets than it did for two consecutive home matches in August. Total announced attendance for those matches was 10,532.

Having a spot in the postseason secured “gives us something to promise our fans,” Rogers said. But players aren’t coasting.

“We know we have to keep up the results to grow this thing,” defender Justin Davis said. “We’re already in the playoffs, but we want three trophies this year so we’ll keep going.”