Tottenham noted that a new head coach will be named in due course, with the club remaining without a league win in 2026.
The game was a must-win for Arsenal in the battle for league title this season.
It is the first time the Red Devils have recorded four successive league victories in almost two years.
The Unify League is a breakaway league proposed in 2021 to rival the traditional UEFA Champions League.
Semenyo said, “First half we played really well. The mentality was to do the same again.”
Anatoliy Trubin sealed the victory for Benfica as the goalkeeper headed home a free kick.
After a wasteful first half with both teams missing several chances to break the deadlock, Barnes opened the scoring for the hosts in the 63rd minute.
Just as Tottenham thought they had nailed the victory, de Ligt headed home a corner kick from Bruno Fernandes to secure a draw for Man United.
The matchday saw Chelsea held to a 2-2 draw by newcomers Qarabag FK, while Pafos FC shocked Villarreal with a narrow 1-0 victory.
Ismaila Sarr put Crystal Palace ahead in the 41st minute.
