Kenneth Zohore kept his cool before Slaven Bilic lost his as West Brom fought back to draw 1-1 in a pulsating Sky Bet Championship encounter at Pride Park.
Zohore scored a late penalty to cancel out Derby's early spot-kick converted by Martyn Waghorn, who then missed another penalty near the end of the first half.
On a sweltering afternoon, Bilic's temper boiled over near the end and he was sent off for protesting but his team continued their unbeaten start to the league campaign.
Derby sprang a surprise by bringing in two 18-year-olds, defender Lee Buchanan for his full debut and midfielder Jason Knight, who was making his first Championship start.
Bilic recalled 18-year-old Nathan Ferguson at right-back as one of three changes but his side were trailing after a rash challenge by Kieran Gibbs handed Derby the initiative.
Waghorn's run into the box was ended by Gibbs' trip and he sent Sam Johnstone the wrong way with a sixth-minute penalty.
Albion responded with Kyle Edwards getting into a good position but shot wide from a tight angle before Ferguson surged down the right and hit a shot which Kelle Roos saved with his feet.
Gibbs was replaced in the 21st minute by Darnell Furlong, who went close with a near-post header from a corner before Derby were controversially awarded another penalty when the linesman flagged for handball against Filip Krovinovic.
Buchanan's cross looked to have hit his shoulder and after Bilic was booked for protesting, Johnstone kept his side in the game when he dived to his left to deny Waghorn in the 43rd minute.
It was his second penalty miss in three home games and the Baggies had a great chance to level in stoppage time but Zohore failed to beat Roos from 10 yards.
The second half began with Knight flashing a low shot just wide but the visitors went close when Matt Phillips whipped the ball across the six-yard box.
Derby had a great chance to double their lead in the 63rd minute when Knight's shot was saved, Jack Marriott sliced the rebound and Kieran Dowell missed his kick before Albion cleared.
Johnstone kept his side on in it two minutes later when he saved Waghorn's volley but Grady Diangana had a low drive pushed away by Roos in the 67th minute.
Albion's final ball had lacked quality but their pressure told in the 84th minute when Max Lowe brought down Matheus Pereira near the byline and Zohore sent Roos the wrong way to level.
Mason Bennett fired wide for Derby and Bilic was dismissed for protesting after Jake Livermore's close range shot deflected off a defender but no corner was given.