The defeat ends England's hopes of reaching a second successive Nations League finals and means Wednesday's final Group A2 match against relegated Iceland will only offer the chance to fine-tune ahead of the Euros.

Southgate was without Raheem Sterling and Marcus Rashford in attack and the likes of Harry Maguire, Joe Gomez and Conor Coady at the back at Den Dreef, where the Three Lions could not quite get to grips with Belgium.

The hosts ruthlessly exploited lax play when Leicester's Tielemans scored in the 10th minute and they extended their lead after Romelu Lukaku's goal-line clearance stopped Harry Kane capping his 50th appearance with a goal.

Declan Rice was adjudged to have fouled Kevin De Bruyne and Mertens bent home superbly as England went into half-time facing a two-goal deficit for the first time since August 2009.

Southgate's men penned Belgium back in the second half as Jack Grealish shone on his first competitive start, but the home side held firm to win Roberto Martinez's 50th match in charge.

England wore black armbands in Leuven following the death of Ray Clemence on Sunday at the age of 72, with the Football Association planning a larger tribute to the former goalkeeper against Iceland.

The Three Lions had hoped to be going into Wednesday's match with a chance of reaching the Nations League finals, but they failed to heed Southgate's pre-match demand to be switched on from the outset.

While Kane dragged wide and Grealish proved a handful in the early stages, such positive work was undone when Jan Vertonghen got ahead of Mason Mount to intercept a pass by Eric Dier.

The ball was moved on quickly and Tielemans got away a shot that the outstretched Jordan Pickford could only tip onto the inside of the post following a slight deflection off Tyrone Mings.

England responded well to Belgium's 10th-minute opener. Grealish was thwarted when meeting a cross from Kieran Trippier, whose resulting corner was met by a Kane header bound for the net until Lukaku cleared off the line.

Grealish had a shot blocked as the visitors looked to stage another comeback against Belgium, only for their uphill battle to steepen when Rice was adjudged to have fouled De Bruyne as he attempted to take a shot.

The Belgium star stood over the tantalisingly-placed free-kick, but it was Mertens that swept in to bend a superb right-footed effort over the wall and into the top left-hand corner midway through the first half.

Mount tried his luck either side of a Kane shot denied by Thibaut Courtois towards the end of a first half that saw England's defensive troubles worsen as Ben Chilwell limped off.

Harry Winks replaced Jordan Henderson for a second period that started with poor free-kick attempts by Mount and Trippier.

The visitors were, though, looking improved and Kane scuffed a shot after being found by a fine Mount flick, with treatment for Trippier giving Belgium a break from mounting pressure.

Jadon Sancho and Dominic Calvert-Lewin were introduced to change the dynamics, with England continuing to push forwards against a side that seemed happy to sit back.

Pickford stopped Lukaku adding gloss to the scoreline after a move involving De Bruyne and Mertens on a rare Belgium attack, while a sumptuous Grealish flick led to a Kane cross-shot that landed on the roof of the net.

The England skipper continued to lead the visitors' attempts but there was no finishing touch, with Lukaku bending wide at the end.