SIEM DE JONG has warned he is unlikely to be back at full fitness by the time Newcastle United take on Leicester City in Saturday’s crucial relegation encounter.

Having made his first senior appearance since suffering a collapsed lung in last weekend’s 3-2 home defeat to Swansea – a game that saw him score his first senior goal since last summer’s move from Ajax – de Jong further stepped up his recovery when he played in Monday’s reserves game with Derby.

The fact the Dutchman remained on the pitch for the full 90 minutes of the second-string game at Derby’s Oakwood training ground has been interpreted as a positive sign of his fitness levels, and led to suggestions that he could start this weekend’s first-team game at Leicester.

Newcastle could certainly do with him in the starting line-up as they will head to the King Power Stadium on the back of a run of seven straight defeats, and with last weekend’s results having dropped them to within five points of the relegation zone.

After missing all bar three of this season’s league games, de Jong is determined to do all he can to aid the recovery mission, but after such a lengthy absence, he has been forced to concede it could still take him another week or so to return to the peak of his fitness levels.

“I’ll try to help the team as much as I can,” said de Jong, who was on his way back from a serious thigh injury when he suffered his collapsed lung in February. “I don’t think if I’m 90 per cent or 95 per cent that I can help the team (from the start).

“That’s why I need to build up slowly to be ready for the minutes I need to play. If I play 90 minutes now, I wouldn’t help the team as much as I could if I waited just another week maybe.”

De Jong’s hesitancy is understandable given that he previously suffered a collapsed lung in 2013 while playing for Ajax.

The problem can be prone to recur, and while the surgery de Jong underwent two-and-a-half months ago should have cleared up the issue as effectively as possible, there is a collective desire not to rush things despite Newcastle’s struggles in the bottom half of the table.

Had de Jong been available for more of the campaign, it is conceivable the Magpies might not be as close to the relegation zone as they are.

The Holland international arrived with a lofty reputation when he completed a £4.5m move from Ajax last summer, and had been earmarked to play in the pivotal number ten role that Newcastle have never really been able to fill in his absence.

The warmth of the reception that greeted his return last weekend suggests Newcastle supporters are aware of just how valuable he could be, and having missed so much football this season, de Jong was delighted to be treated so favourably.

“I was glad to hear (the applause) when I was warming up along the line,” he said. “It was just a shame my goal wasn’t enough in the game because the important thing is to get points.

“We have to focus on that, but I have a little bit of an agenda myself, which is to get 100 per cent fit and help the team as much as I can.”

Meanwhile, Adam Campbell has had a trial with West Brom’s development team as he plans for life away from St James’ Park this summer.

Campbell, whose Newcastle contract is due to expire at the end of the season and will not be renewed, lined up for the Baggies’ second string as they claimed a 3-0 win over Arsenal.