Leading 13-7 at halftime, the AP Preseason All-American turned up the heat in the third quarter, connecting on touchdown passes of 33 yards to David Sills, 28 yards to Gary Jennings and 14 yards to Kennedy McCoy to help the Mountaineer open a 33-14 lead.
Grier, who grew up in the Charlotte area and once threw 10 TD passes in a high school playoff game, was 14-of-19 passing for 275 yards and four TDs in the second half against the Vols.
Sills, who totaled 18 touchdown receptions last season, had seven grabs for 140 yards and two TDs.
Tim Jordan ran for 118 yards on 20 carries and a touchdown for Tennessee, which lost in Jeremy Pruitt's head coaching debut. Pruitt won six national championships as a defensive coach, including last year at Alabama, but his Vols had no answer for Grier and the high-powered Mountaineers offense.
The game was delayed for more than an hour at halftime because of lightning.
Tennessee: Jarrett Guarantano got the starting nod at quarterback over Keller Chryst and struggled at times. The Vols had only one passing play of longer than 20 yards and Guarantano was limited to 172 yards passing.
West Virginia: While Grier lived up to his preseason hype, what might have been most impressive for the Mountaineers was the play of their defense in holding the Vols to just two touchdowns. They set the tone for the game by forcing Tennessee to go three-and-out on the game's first possession after two tackles for a loss of 15 yards.
Tennessee: The Vols lost running back Ty Chandler to an ankle injury in the first half. He did not return.
West Virginia: Linebacker Charlie Benton left the game in the first half with a sprained knee and did not return.
Tennessee: Returns home to face East Tennessee State next Saturday.
West Virginia: Will be a big favorite at home against Youngstown State next Saturday night.
No. 17 West Virginia 40, Tennessee 14
West Virginia 10 3 20 7 — 40
Tennessee 0 7 7 0 — 14
WVU—FG Staley 26, 11:00
WVU—Simmons 59 pass from Grier (Staley kick), 3:32
TEN—Wood-Anderson 1 pass from Guarantano (Cimaglia kick), 6:13
WVU—FG Staley 35, :00
WVU—D.Sills 33 pass from Grier (Staley kick), 12:54
WVU—G.Jennings 28 pass from Grier (Staley kick), 8:09
TEN—Jordan 4 run (Cimaglia kick), 6:09
WVU—McKoy 14 pass from Grier (pass failed), 1:15
WVU—D.Sills 10 pass from Grier (Staley kick), 2:02
First downs 26 19
Rushes-yards 27-118 38-129
Passing 429 172
Comp-Att-Int 25-34-0 19-25-0
Return Yards 51 77
Punts-Avg. 1-47.0 6-38.16
Fumbles-Lost 1-1 1-0
Penalties-Yards 4-35 6-48
Time of Possession 27:37 32:23
RUSHING—West Virginia, Pettaway 9-56, L.Brown 8-33, McKoy 4-18, Simms 1-5, Sinkfield 1-4, Bush 1-2, Grier 3-0. Tennessee, Jordan 20-118, London 5-12, J.Banks 5-11, Palmer 1-7, T.Chandler 4-(minus 4), Guarantano 3-(minus 15).
PASSING—West Virginia, Grier 25-34-0-429. Tennessee, Guarantano 19-25-0-172.
RECEIVING—West Virginia, D.Sills 7-140, G.Jennings 6-113, Simms 2-40, Wesco 2-35, Sinkfield 2-15, Simmons 1-59, McKoy 1-14, Haskins 1-9, Maiden 1-8, Bush 1-1, Pettaway 1-(minus 5). Tennessee, Callaway 7-85, Palmer 3-33, J.Jennings 2-29, Jordan 2-11, J.Banks 1-10, Murphy 1-5, Wood-Anderson 1-1, B.Johnson 1-1, Tillman 1-(minus 3).
MISSED FIELD GOALS—None.