The two clubs, who play each other on Sunday, are level on 75 points heading into the final two games of the season, with Genk three behind.
Antwerp will be crowned champions with a game to spare if they win at the weekend due to the tiebreaker rules, while if Union upset their hosts, they will then need one point from their last game of the season at home against outgoing champions Club Brugge on June 4.
While Genk cannot yet be counted out, only the two at the top have their title destiny in their own hands.
Antwerp’s measly list of achievements belies their status as one of Belgium’s best-supported clubs, having won the last of their four Belgian league titles in 1957.
But their 66-year drought is nothing in comparison to Union, who were the most successful Belgian side before the outbreak of World War Two with 11 championships but last won the title in 1935.
The Brussels-based club won promotion back to the top flight after a 48-year absence ahead of last season and were on course for a fairytale 12th title before being caught in the closing stages of the campaign by Club Brugge.
This season they are looking to go one better and win their first title in 88 years in an incredible rise out of the doldrums, benefiting from their partnership with Brighton & Hove Albion, whose owner Tony Bloom also has a stake in the Belgian outfit.
But home advantage makes Antwerp favourites to deny Union.
Antwerp’s emergence this season - they are on course for the double after beating KV Mechelen in last month’s Belgian Cup final - comes with a heavy dose of Dutch influence, having appointed Marc Overmars as technical director and Mark van Bommel as coach.
The former Netherlands players have been credited with turning the team into contenders, with Dutch international striker Vincent Janssen contributing 17 goals.
The Belgian league plays a regular season of 34 games, after which the top four teams advance to a playoff round to decide the title.
They carry over half of the points they won in the regular season, rounded up to the nearest number. The points gained by rounding are deducted in the case of a tie, meaning Antwerp, who gained no extra points compared to their rivals, will secure the title with victory on Sunday.
