Forest boss Stuart Pearce believes Assombalonga will prove a bargain buy at £5million this season and the former Peterborough marksman started to repay his big fee with his first goals of the new campaign including a 37th-minute penalty.
Joe Mason, signed from Cardiff earlier in the week, headed Dougie Freedman’s team in front. David Wheater then restored Wanderers lead before Assombalonga ensured the home side are still waiting for their first Championship success of the season from the spot.
Forest could possibly have been ahead before Mason made his mark on his latest return to the Trotters.
A poor back header by vice-captain Matt Mills let in Assombalonga but the former Posh favourite’s pass was tamely finished by Matty Fryatt.
So, it was doubly painful when skipper Jay Spearing swung in a superbly floated free-kick and Mason rose highest to head home from six yards after four minutes.
Wanderers held their lead thanks to Adam Bogdan’s double save from Andy Reid and Fryatt. But they only repelled the visitors until the 26th minute as Assombalonga celebrated his first goal for his new club.
Chris Burke’s left foot cross from the right was headed down and across goal by Michail Antonio and Assombalonga lashed home from eight yards.
Fortunately, for Bolton, the visitors’ defence was equally porous and defender Wheater restored the home side’s lead two minutes later.
Forest failed to clear their lines following another Spearing free-kick and as the ball trickled back in across the area, unmarked Wheater probed home from five yards with keeper Karl Darlow flat-footed.
However, Forest restored parity eight minutes from the break, after Spearing recklessly flew in to bring down Assombalonga.
The former Liverpool midfielder protested his innocence but there were few complaints from his team mates. Adam Bogdan tried to psyche out Assombalonga by dancing along his goal line but Assombalonga thumped the spot kick through the Hungarian international’s legs.
Spearing’s anger then spilled over, scything down Chris Cohen and promptly receiving the game’s first yellow card
Forest, without suspended Michael Mancienne, sent-off in the midweek Capital One Cup victory at Tranmere, maintained the momentum at the start of the second period.
And Assombalonga looked the player most likely to score again. A decent cross from Antonio was met by the imposing forward and Bogdan was grateful to see the ball trickle by his post.
Andy Reid tried to cheekily chip Bogdan from wide on the Wanderers left before the home side finally broke out. And they should have sneaked all three points as Craig Davies headed over from six yards after Kevin McNaughton supplied a superb right wing cross.
But after the flurry of first-half excitement there were no further goals as Forest protected their unbeaten start.