Estoril midfielder Antef Tsoungui is a target for both Rangers and Southampton, sources have told ESPN.
The highly-rated 23-year-old was the subject of interest from French side Saint-Etienne earlier in the summer.
Sources have told ESPN that Estoril are looking for a fee of between €5 million and €6m ($5.8m - $7m).
Both Rangers and Southampton are among a host of clubs monitoring the Belgium Under-21 international. There's also interest from across Europe, including from Bundesliga clubs.
Born in Belgium, Tsoungui came through the youth set-up at Chelsea before spells at Brighton and Feyenoord.
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He stood out in Primeira Liga last season, ranking fifth for most ball recoveries in his own half and third for most defensive ground duels won against other defensive midfielders in Portugal's top-flight.
Sources have told ESPN that Tsoungui's proposed move to Saint-Etienne collapsed because the two clubs could not agree on a fee.
Southampton are looking for reinforcements before the transfer deadline while Rangers are keen to back new manager Derek McInnes after a mixed start to his reign at Ibrox.