Leeds United's newest midfielder Weston McKennie came off the bench late on to make his Premier League debut but could not stop his side from suffering a 1-0 defeat at the City Ground on Sunday.
Forest's Brennan Johnson scored the winner but it was debutant goalkeeper Keylor Navas they had to thank for the gritty home victory.
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The 36-year-old Costa Rican, signed on loan from Paris Saint-Germain until the end of the season, pulled off a string of superb reflex saves to deny a Leeds side who dominated possession, but could not find a way past him.
Forest took the lead against the run of play when Leeds defender Pascal Struijk fouled Johnson and compounded the error by botching his headed clearance from the free kick, teeing up a chance for Johnson.
The Welsh forward needed no further invitation, firing a rasping volley into the net to breaking the deadlock with his side's first effort on target.
The visitors could have levelled but Luis Sinisterra blasted his effort high over the bar with the goal at his mercy, and when Leeds managed to get efforts on target Navas reacted smartly to keep them out.
Neco Williams almost netted a second for Forest with an early second-half breakaway but he blazed just over the top-right corner after a lung-bursting run from midfield, and after that, the home side made few forays forward in the second half, preferring instead to sit back and defend.
They cleared their lines repeatedly and conceded possession to Leeds, but the visitors struggled to create chances despite enjoying the lion's share of possession, allowing Navas and Forest to coast to a win in his debut.
The win extended Forest's unbeaten run in the Premier League to five games and moves up to 13th in the table on 24 points.
"What a debut [for Navas], massive, massive saves. He kept us in it and we're thankful for him," Williams told the BBC after the match. "What a career he has had and what a career he is having. It's not easy making your Premier League debut against Leeds.
The Forest defender said his side were starting to find their feet after a difficult start to their Premier League campaign.
"The start of the season was tough, no one knew each other it was hard to get the chemistry on and off the pitch. Now we're gelling together and the results are coming," he said.
The loss leaves Leeds hovering above the relegation zone on 17 points and without a win in the Premier League since beating Bournemouth on Nov. 5.
