Millers manager Steve Evans maintained before kick-off that this would be his side’s toughest test so far in the Championship.
Some compliment to Watford, last night’s visitors to New York Stadium, as the newly-promoted Millers had opened up their campaign in the second tier against the might of Derby County and Wolves.
Rotherham gave them loads of trouble in the first half, but Evans was proved right as Watford settled the match after the break with goals from Lloyd Dyer and Gianni Munari.
It was the home side who started better, playing their slickest football of the season in a 4-5-1 formation as they set about the visitors.
The extra man in midfield was making a big difference and, aptly for a team facing the Hornets, the Millers buzzed around with skill, composure and slick passing, keeping possession and asking continual questions of well-organised opposition.
They looked a real Championship team, losing nothing in comparison to the team Evans rates so highly, although some of their precision left them after the break as Watford upped their game
Richard Smallwood, back from Middlesbrough for a second loan spell, broke up Watford play, was always available to a teammate and hardly misplaced a pass.
Paul Taylor, fast, direct and with a killer touch, troubled the visitors constantly in the first half and had his moments in the second too.
Their best chance of an entertaining first half came in the dying seconds as Lee Frecklington drilled in a fierce effort after being fed by one of many Alex Revell head-ons which was just pushed wide by Heurelho Gomez.
Revell had twice been wide with difficult efforts and Ben Pringle tested former Spurs goalkeeper Gomes with a curling 29th-minute effort.
Craig Morgan produced a huge leap from the ensuing corner and headed just over, before Taylor’s perfect control saw him sprinting towards goal only to fire over.
For Watford, Troy Deeny thought he should have had a penalty in the 25th minute when he tangled with Adam Collin.
The referee might have got it wrong and the fuming Watford striker let him know as he threw his Troys out of the pram.
Taylor was close to an opener just 54 seconds into the second half when he scooped over from Pringle’s feed, and sustained cries of “Red Army” rang round the New York as the fans appreciated what they were watching.
Rotherham had a scare on 61 minutes when an Ighalo effort was correctly ruled off for offside, but Watford had gone 60 yards in a matter of seconds and it showed how fast the visitors could be on the break.
Taylor was over from a free-kick just outside the area, but Watford were coming more into the game and sub Lloyd Dyer, on the pitch for only nine minutes, fired home, following up a shot by fellow sub Odion Jude Ighalo.
Rotherham’s response was almost Swift.
Teenager John had just come on for Pringle when he was inches over with a sweet curler.
In the 86th minute Taylor floated in a perfect free-kick which eluded all the Watford defenders but no Miller could quiet get on the end of it.
A minute later, 2-0 to Watford, Gianni Munari finishing off from close range as Tommie Hoban crossed.
Rotherham, as Rotherham do, kept going to the end and Taylor volleyed just over from close range as the game drifted into time added on.
But clinical Watford had showed just what the Championship is all about.
Teams are strong and carry threats throughout their line-up. Main men Deeney and Matej Vydra were kept quiet all evening. Yet the points headed south.