The CW's The Flash premiere was a massive ratings hit last night, scoring a 1.8 adults 18-49 rating, making it the CW's most-watched and highest-rated series debut since The Vampire Diaries premiered in 2009.

It also managed to do outscore Marvel's Agents of S.H.I.E.L.D., which also aired last night, in the 18-49 demographic. Given that S.H.I.E.L.D. airs on ABC and The Flash on The CW, that's quite an achievement.

TV By the Numbers has the results, saying that Marvel’s Agents of S.H.I.E.L.D. earned a series low 1.6, down two tenths from last week's 1.8 adults 18-49 rating -- but last week, the series was supposedly at a new low before it was adjusted up in the final Live + Same Day ratings. If the Live+SD gets the same (roughly 10%) bump this week, it will tie last week. That will still make it tied for the series low, but not a new low.

The Flash finished third in the 8 p.m. hour with a 3.4/ 5 overall, which was The CW’s highest-rated premiere in the overnights since The Vampire Diaries in 2009. TVLine notes that The Flash came in 166% higher than last year's premiere of The Originals did in the same time slot -- and The Originals got renewed for a second season. It also beat the first hour of special The iHeartradio Music Festival, which screened on The CW last Tuesday, by 386%. It outdelivered the series premiere of Arrow by 13% and even managed to gain one-tenth of a rating point (or three percent) at 8:30 p.m. (3.3/ 5 to 3.4/ 5). Like S.H.I.E.L.D. and Arrow, the series is also expected to score big on social media and DVR, which will help the live plus 3- and ten-day ratings numbers.

The CW has made the pilot for The Flash available online, so if you missed it, check it out here.