And they are confident the visit of the former Portuguese champions – their only home friendly – will attract a healthy crowd.
Chief executive Brenda Spencer told the Evening Post: "We had been looking for a high profile club to play on the Saturday before the season and the chance to play Boavista came about.
"We had other friendlies arranged but nothing to really push the players, so when this opportunity arose, Paul Jewell encouraged us to go for it.
"I signed the agreement to play them in London yesterday and it's a very exciting fixture to look forward to.
"Last week we also got a game against Preston arranged after they lost in the play-off final, so we now have a nice balance of fixtures.
"Boavista are a strong side, finished sixth in the league this season, and this game will ge a great curtain-raiser for our debut in the Premiership."
Boavista won the Portuguese league in 2000/01 season, reached the second phase of the Champions League the following year, and were UEFA Cup semi-finalists in 2003.
The other friendly fixtures for Latics' first team squad are Preston (a) on July 27, Macclesfield (a) on July 30, and Morecambe (a) on August 2.
There are games at Burscough on July 28, Southport on August 3 and Accrington on August 6 for the reserves.
Jewell is also taking the squad to Denmark in mid-July for a behind-closed-doors training camp.
On the transfer front, Latics appear to be on the trail of striker Leon McKenzie again, as they seek to bolster the squad.
Jewell tried several times to sign McKenzie when he played for Peterborough, before the former Crystal Palace trainee opted to join Norwich instead.
Last season he scored seven goals in the Premiership but his efforts weren't enough to save the Canaries from relegation on the final day of the season.
McKenzie is reportedly being eyed up by a number of clubs but Latics appear to have more financial clout.
One sticking point, though, could be the 27-year-old's reluctance to move north, with him preferring to stay nearer his London roots.
Jewell wants to strengthen his attacking options with Jason Roberts and Nathan Ellington both nursing injuries at the moment.
And he doesn't want the pair to shoulder the goalscoring burden on their own, hence the link with McKenzie and also Brett Ormerod, who spent six weeks on loan at Latics towards the end of the season.
If they do land McKenzie, it could be he will be swapping clubs with Jason Jarrett, who is attracting Norwich's attention.
Jarrett has been offered a new three-year contract by Latics but with his current deal up soon, is entitled to speak to other clubs.
Norwich expect to lose Damien Francis from their midfield this summer
and are searching for a replacement.
Latics haven't had an answer yet from Jarrett over his future, Jewell saying: "We've made him a fair offer and have been negotiating with his agent.
"He is a free agent from July 1 and is allowed to speak to other clubs to see what is available."