Smith made it 3-2 at 4:04 of the third period when Jonathan Marchessault's shot off a scramble in the low slot went in off him.
Marchessault played 17:04 in his return after missing the previous five games in NHL COVID-19 protocol.
Oilers forwards Leon Draisaitl, first in the NHL with 40 points (20 goals, 20 assists), and Connor McDavid, whose 36 points (14 goals, 22 assists) are tied for second with Alex Ovechkin of the Washington Capitals, were held without a point in the same game for the first time this season.
"Not a lot of teams have kept those guys off the score sheet," Smith said. "There's more to that team than just those two players. The three or four breakaways that we gave, that's what cost us."
NOTES: Hyman has 95 goals and 105 assists in 365 NHL games (345 with Toronto Maple Leafs, 20 with Oilers). … Nugent-Hopkins is two points from 500 in the NHL (498 in 676 games; 187 goals, 311 assists). His goal was his 20th point of the season. ... The Oilers have three players (McDavid, Draisaitl, Nugent-Hopkins) with at least 20 points through the first 20 games for the first time since they had six players in 1988-89 (Mark Messier, Glenn Anderson, Craig Simpson, Jimmy Carson, Esa Tikkanen, Jari Kurri). ... Stephenson extended his goal streak to three games, an NHL career high. ... DeBoer coached in his 99th regular-season game with the Golden Knights. He is 67-28-4 since Vegas hired him Jan. 15, 2020.