Oct 5 (Reuters) - Norway striker ⁠Erling Haaland is showing signs of physical fatigue following a relentless run of matches for club ⁠and country, raising concerns over his punishing workload.

The 26-year-old Manchester City forward was substituted after ‌67 minutes as Norway lost 2-1 away to Portugal in Nations League Group A4 on Sunday.

Haaland was among several high-profile players who left the stadium straight after the match on a private jet to make the most of a brief holiday before returning to ​club duties.

"He was simply thoroughly spent," Norway manager Stale Solbakken said ⁠of Haaland's condition.

"Some of my players have ⁠only had six or seven days of holiday. And you do not live off your physical condition in ⁠a ‌normal job. Then it is straight into the start of the season, followed by a mini-tournament, so it is an extreme strain."

"He’s in the group that carries the heaviest workload — precisely because his ⁠team (Manchester City) plays in every tournament and he’s the main man," ​Solbakken added.

Norway midfielder Patrick Berg ‌echoed his manager's assessment, noting the physical toll on Haaland.

"He has played all three (Norway) games before ⁠this one, so it's ​not that shocking his strength finally ran out," Berg said.

Haaland has endured a gruelling schedule in recent months. Norway's run to the World Cup quarter-finals significantly cut short his off-season and he has since featured in every Premier League match ⁠for City, scoring five goals.

Haaland highlighted the relentless schedule on ​social media after a two-goal performance in the 3-2 Nations League win over Denmark last month, posting: "So tired. New match in 70 hours."

NORWEGIAN PLAYERS' UNION CONCERNED

Norwegian players' union NISO expressed concern over the escalating match schedule for the ⁠country's leading athletes.

"Over time, we have seen a worrying trend where the burden on top players has become far too high," NISO chief Kristoffer Vatshaug said in a press release on Monday. "It has already had consequences for several players. This is serious.

"We want clearer guidelines for workload and recovery. It is about the time ​between matches, consecutive rest periods, travel strain and how much time players ⁠get to recover after a long season."

Vatshaug said the responsibility does not rest with individual players.

"We cannot have a ​system where protecting players depends on them saying stop themselves. Footballers ‌want to play football. They want to turn out ​for their club, national team and teammates."

Haaland has six days to recover before City resume their Premier League campaign at Liverpool on Sunday.

(Reporting by Tommy Lund in Gdansk; Editing by Ken Ferris)