The hosts sit just two points above the relegation zone now, whereas the visitors have won their last two games to rise up to seventh.
The trajectories of these two clubs could hardly have been more different in recent weeks, with Belenenses picking up only three points from the last 15 on offer and Rio Ave springing into form.
Friday's visitors had been winless themselves prior to their last two games, but successive victories and clean sheets have seen them leap from the lower reaches of the table to within one point of the top four.
Not since January have they won three consecutive league games, and you have to go back to April 2016 for the last time they kept three clean sheets on the bounce too.
It had been a disappointing start to the season for Mario Silva's side as they were made to wait for their first win, but those back-to-back victories have changed the perspective of their season and now the more eye-catching statistic is that they have only lost one of their opening six games - and that was against Benfica.
By contrast, Belenenses got their campaign off to a dream start with an away win over Vitoria Guimaraes, but have since embarked on a five-match winless streak.
Petit's side have not exactly been the entertainers in that time either, with their six matches this season yielding a sum total of only eight goals - three for and five against.
Even so, six points on the board after as many games is not a disastrous start for a club that flirted with relegation last two season, but their wider form will be a greater concern if they are to avoid another battle at the bottom this time around.
Since the restart in June, Belenenses have only won three of their 16 Primeira Liga outings, and the division's lowest goalscorers have failed to net more than once in a game in any of their last 15 attempts.
Belenenses Primeira Liga form: WLDDLD
Rio Ave Primeira Liga form: DDDLWW
Rio Ave form (all competitions): DLDLWW
Out: Junio (broken leg)
We say: Belenenses 0-1 Rio Ave
These two sides have not been finding the back of the net with much regularity this season, so this looks as though it could be a low-scoring affair. Rio Ave arrive in better form, though, and we expect them to make it three wins on the bounce here.