Saliba played 45 minutes in Sunday's 5-2 victory over Aston Villa at Boreham Wood, taking an important step towards full fitness after a three-and-a-half-month absence. The appearance was planned as part of his rehabilitation, with the France international needing match minutes before returning to Mikel Arteta's first-team squad.
Although Saliba's quality on the ball was evident, Horseman was just as impressed by the way the 25-year-old approached the occasion and interacted with the younger players.
“He’s the ultimate professional from the minute he got in this morning to half-time. He’s fine, by the way, it was all pre-planned, so nobody needs to panic.
“Just the way he was in the meeting, everything about him, the way he prepares on the bus, the lads probably won’t notice it, but they should.
“The way he coaches and talks on the pitch, and then his quality, like the pass from Max [Dowman] to slip in Marcell [Washington] for Andre’s [Harriman-Annous] first goal. The detail of play, and he mixed his game up between short and long.
“Obviously, everybody knows he’s a world-class defender, one of the best in the world, if not the best. It was brilliant, but he was so good around the lads, you’d never know it.
“He’s a brilliant pro, great guy, and we’re really thankful for him to act like that, because if he does it, there’s no excuse for the rest not to do it. It was brilliant having him. I’d love him every week. Obviously, that’d be lovely, but he’ll leave us soon and go back with the first team.”
Saliba's presence helped Arsenal's under-21s secure their first league victory of the season. The Gunners recovered after falling behind to win 5-2, with Andre Harriman-Annous scoring twice and Maalik Hashi, Max Dowman and Evan Mooney also finding the net.
Marli Salmon, another member of the senior setup, captained the side, while Dowman also featured as Arsenal called upon first-team players to strengthen the young team.
Saliba's passing range and composure stood out during his half on the pitch, but Horseman was keen to stress that his conduct offered an example beyond the technical aspects of his performance. The defender did not behave like a senior star making a temporary appearance; instead, he embraced the group and contributed to the players around him.
The defender had returned to the first-team matchday squad for the Champions League fixture against Slavia Prague, having missed the previous three-and-a-half months. He was not included in the senior squad for the weekend match against Hull, with the club instead arranging his under-21 appearance to build his fitness.
The next challenge for Horseman's side is to maintain the standards shown against Villa when senior players such as Saliba, Salmon and Dowman are no longer available. For Saliba, the priority is to complete his return to fitness and rejoin Arteta's squad.