STEVE BRUCE will stick with his new formation for this afternoon’s game at Southampton, but the Newcastle United manager admits the trip to St Mary’s represents an “acid test” of his side’s ability to maintain their defensive resilience with a flat back four.

Bruce switched from playing with five at the back ahead of last weekend’s goalless home draw with Burnley and stuck with his new 4-2-3-1 formation as his side won at West Brom on Tuesday to reach the quarter-finals of the FA Cup.

If he avoids further tactical changes this afternoon, it will be the first time Newcastle have played in a Premier League away game with a flat back four since they collapsed to an embarrassing five-goal defeat at Leicester City in September, and Bruce admits Southampton’s attackers will ask some difficult questions of his centre-halves.

“I think we were a bit unfortunate at Leicester, when we went down to ten men, and that made it difficult to judge, but this will be the acid test (of playing with a flat back four),” said the Newcastle boss. “I do believe it makes us more of a threat, and you saw that when we went to West Brom and scored three the way we did.

“We have to score a goal, and that’s what we’re trying to do. It’s more like the way I want to play, and I’ve said that from day one. When results aren’t going for you, the only thing a manager or coach can do is change the personnel or change the system. I thought changing the system might just suit everybody.”

One of the key results of the change in system has been a switch to where Miguel Almiron finds himself stationed, and the Paraguayan is clearly revelling in his move infield to a more central attacking-midfield position.

Since moving to Tyneside from the MLS 14 months ago, Almiron has spent much of his time playing on the flank, but his best performances for Atlanta United tended to come in the ‘number ten’ role and he looked a much more threatening proposition playing infield on Tuesday night as he scored the opening two goals in Newcastle’s FA Cup win.

“He’s a good player, and I think we’ve brought him back to life a little bit playing in his best position,” said Bruce. “For me, his best position is certainly as a number ten. Unfortunately, because of the system we’ve had, we’ve tended to play him from the side. But this has certainly helped him and means arguably our best player is playing in his best position.

“I think he lit Newcastle up before I came here – last January he was the big tonic that everybody needed. He then got injured, but for 12 months or so, I think everybody had been wishing him a goal.

“He’s a really, really good player. Unfortunately, if you play in his position, you get judged on goals, which for me is not quite right because since I’ve been here, he’s been very, very good. He’s a wonderful team player.”

Bruce must decide whether to reinstate Dwight Gayle into the starting XI, with the striker having sat out Tuesday’s cup win after starting against Burnley.

If Gayle starts, it is hard to see how Bruce can fit Almiron, Joelinton and Allan Saint-Maximin into the same starting side without making his team badly unbalanced. He will be reluctant to drop Joelinton after backing the Brazilian so forcefully over the last few months, so Saint-Maximin could find himself on the bench despite having come through Tuesday’s game without a recurrence of his back and hamstring issues.

Newcastle (probable, 4-2-3-1): Dubravka; Manquillo, Fernandez, Lascelles, Rose; Shelvey, Hayden; Ritchie, Almiron, Joelinton; Gayle.