Composer: John Deacon
Meter: 4/4
Key: G-Major, Bb-Major ( > C > Db > Eb )

       Intro I-II(A) | Chorus (A)| Verse I |
                     | Chorus    | Solo    |
                     | Chorus    | Verse I - II - outro  

While not a mega-hit of the era it's definitely an important point of the Queen songbook being the first public composition of Deacon. It's under two minutes and its songform is more or less cyclic. We have an oddly harmonized guitar solo section where from the harmony is shifted up. The outro applies a chain of key-shifts.
There is some Beatles-ism in two chord progressions and in the assymetric mixing.

The intro starts with strummed guitars setting the homekey. The harmonic rhythm is 3+5 syncopated.

| G C  | -    |
| I IV | -    |

The second part of the intro is in fact the backing track of the Chorus. The arrangement is completed with bass and   multitracked (three-part) guitars figure which is the main hook of the chorus and the outro.

It's only four measures with two pentatonic melodic phrases (AB-AC 2+2). The lead vocal is mixed into the left channel (> "Who Needs You"), balanced out with multitrack guitar figures. Note how both notes of "fill me U-UP" are non-triadic (B and D notes vs. C chord).

| G C  | -    | -    | G D  |
| I IV | -    | -    | I V  |

The third verse is shifted up to Bb-Major.

The verses are steering the harmony toward the relative minor key (e-minor). The harmonic phrasing is AAA 2+2+2 the melodic phrasing is AA'A" 2+2+3 the last phrase overlapping the next chorus. The lead vocal is mixed into the right stereo channel.

/----- 3x ----\\
| Em   | A C  || G...
| vi   |II IV || I
The vi > II > IV > I progression can be familiar from "She Loves You" (Beatles).

The second verse is extended with a rising melodic phrase. The arrangement drops the guitar harmonies and adds simple vocal harmonies following the guitar chords.

| Bb   | C    | Eb   | -    || Bb...
| I    | II   | IV   | -    || I

This chord progression is familiar from "Eight Days A Week" (Beatles), but see also later in "A Kind Of Magic".

The guitar solo features many triadic fragments. The harmony is too vague to speak about fixed tonal center here. The first chords are reminiscent of the "I > V > bVII > IV" lick while the ending is a step-wise shord stream. In m4 we have a 3+3+2 rhythm pattern putting the last chord change one quarter before the downbeat.

| Eb  | Bb Db |
| Ab  | Db7 Eb7 F7 | (F)  |
        Bb: IV  V  |  V   |

The guitar chords are strenthened with simple vocal harmonies. The caribic drumfill of the closing is reminiscent of "Who Needs You".

The beginning of the outro overlaps the last verse. The mulititrack guitar fills are varied as the key is shifting up:

m.1-4  Bb-Major
m.5-6  C-Major
m.7-10 Db-major
m11-   Eb-major

The closing antiphonal guitar fills with 3+3+... (6+6+...) grouping of notes are reminiscent of the closing of "Killer Queen".