The young Magpies take on the Saints' second-string at the Staplewood Training Centre (kick-off 7pm GMT) and kicked off 2023 with a 2-0 home defeat at the hands of Aston Villa's second-string on Monday night.
Diallo, who joined United's Academy in October 2022 following a successful trial with Newcastle's under-21 side, believes his side, currently three points adrift of the Division Two play-off spots, were unfortunate to leave empty handed against the Villans but vows to bounce back positively against the Hampshire-based outfit.
The 19-year-old, who primarily plays on the left wing, told nufc.co.uk: "We're really looking forward to playing on Friday because we thought that we should have had a better result on Monday. Sometimes, in football, it doesn't always go in your favour but we'll be determined to try and get a win against Southampton.
"We were unable to convert the chances we created. I thought we had a lot of opportunities to score in that match and the timings of their goals didn't really help us, especially the second goal. Next time, we need to make sure we take them.
"We're all confident we can go down there and match them in every way, working hard to try and get three points.
"Every game is a big one from now because we need to do everything in our powers to get into the play-offs to try and get promoted at the end of the season. That's the biggest aim."
Since joining the Magpies' youth set-up in October, Diallo admitted he has relished moving hundreds of miles away from his hometown of Canning Town in East London to Tyneside, his first venture from the capital.
The former England Under-17 international, who signed his first professional contract with West Ham United in February 2020, is aiming to build on his development both as a player and person.
The teenage winger added: "It's been good so far and I've settled in very quickly. The lads and staff have been very good to me and I need to kick on and make sure I can help the team out.
"I've been enjoying the matches, training and the togetherness of everyone here. There's a lot that I have learnt.
"It's a new experience for me moving to Newcastle. I have to pick up things myself and adapt but I think I'm doing that. I'm always learning, becoming more independent, and growing as an adult which is important as you never know where you can go in football."
