Southampton boss Ronald Koeman looks to have won the race for the in-demand duo, thwarting Newcastle and Sunderland for Belgium defender Alderweireld and Tottenham for Senegal striker Mane.
Atletico Madrid centre-back Alderweireld and Red Bull Salzburg forward Mane could both command sizeable fees as the south coast club continue reshaping their squad after the summer exodus.
Former Ajax defender Alderweireld is seen as a direct replacement for Dejan Lovren, who joined Liverpool this summer.
Versatile Salzburg forward Mane has scored 45 goals since his 2012 transfer from Metz, and would add to Koeman's attacking options, able to operate across midfield as well as up front.
Saints' move for Mane came after the club baulked at the chance to pursue Tottenham winger Andros Townsend.
The England international had been strongly-linked with a move to St Mary's, with reports he could have formed part of a deal which would see Jay Rodriguez go the other way.
Saints were only keen to allow fringe players to leave St Mary's ahead of Monday's transfer deadline, with the club reaffirming their commitment to retaining talents like Rodriguez and Morgan Schneiderlin.
Southampton confirmed on Monday afternoon they had agreed to terminate midfielder Saphir Taider's loan spell from Inter Milan - less than a month after joining the club.
The 22-year-old Algeria international moved to St Mary's on a season-long loan on August 6, with a view to signing permanently from Inter
The deal also saw club-record signing Dani Osvaldo go the other way.
However, a club statement on Monday read: "The midfielder joined Saints for the 2014-15 campaign but, having failed to live up to the high levels of commitment expected of Southampton players, that arrangement has been cut short by the club.
"Taider, whose only first-team appearance came in the friendly against Bayer Leverkusen earlier this month, now returns to parent club Inter Milan
Dani Osvaldo's loan arrangement with the Italian side is unaffected."
Saints academy graduate Jake Sinclair joined Scottish Championship club Hibernian on a season-long loan deal on Monday.
The development squad youngsters has risen through Southampton's ranks since joining the club aged eight, and signed a one-year deal in July.
Source : PA
Source: PA