Thierry Henry provided the inspiration with Arsenal's first-ever Champions League hat-trick to ensure that Arsene Wenger's side made the perfect start to their second group stage in Rome.

Having swept to the Premiership title on the crest of an attacking wave, Arsenal always needed to show defensive maturity if they were to ever conquer Europe.

While the Gunners needed more than a hint of good fortune, with a strong penalty claim turned down and Pascal Cygan producing a superb goalline clearance, they produced a dogged display full of determination.

And the real difference between the two sides was clear - the peerless finishing quality of Henry, who put illustrious counterparts such as Francesco Totti and Gabriel Batistuta to shame.

The Frenchman not only equalised Antonio Cassano's early strike within just two minutes but also struck twice in the second-half, firstly through pure instinct and then with a free-kick of the highest quality.

In doing so, he ensured that Arsenal hold the upper hand in a group also including the champions of Spain and Holland, with Valencia and Ajax drawing 1-1 in the other game.

All this came even after Arsenal suffered a blow before kick-off, when David Seaman was ruled out by a recurrence of his groin injury, although Oleg Luzhny was fit to start at right-back instead of rookie Moritz Volz.

Wenger's side were soon under pressure and while Sol Campbell and Cygan manned the barricades in the first couple of minutes, just as effectively as they did for the rest of the game, Arsenal's resistance was short-lived.

Cassano turned Campbell inside and out before clipping a shot against the inside of the near post and, although the ball initially rolled along the line, it span just inside the other upright at the last moment.

But while Arsenal were behind after just four minutes, they were level within a further 100 seconds as Henry provided the perfect riposte.

Gilberto - up against a Roma midfield featuring Brazilian counterparts Lima and Emerson - slotted a through-ball to the Frenchman, who showed unflappable composure in stroking his shot inside the far post.

Henry's next effort was held by keeper Francesco Antonioli, but the effect of his equaliser was considerable in helping to settle Arsenal's nerves after such a shaky start.

They certainly enjoyed their fair share of midfield possession and keeper Antonioli had to rush smartly off his line to prevent Gilberto converting a dangerous cross from Ljungberg.

Roma were nevertheless increasingly asking their own questions of an Arsenal defence, which has been prone to lapses of concentration over recent weeks.

Totti struck a volley which appeared a certain goal before an acrobatic last-ditch clearance by Cygan saved the day, while two penalty claims went unheeded.

The decisions were nevertheless going Arsenal's way, although it was some of the less crucial ones that were the most perplexing.

Cygan still produced another crucial interception as Arsenal's defence, who were playing a dangerous offside trap, seemed to teeter on the brink before steadying themselves once again.

Arsenal made a relatively confident start after the break and while Campbell played Totti onside, he redeemed himself with a superb interception from Cafu's ensuing cross.

Roma did not waste time in making their first substitution and Gianni Martinez Guigou almost made a dramatic arrival in seeming to have earned a penalty when he was apparently brought down by Rami Shaaban.

However, referee Lubos Michel waved aside the Italian side's most convincing spot-kick appeal yet and the stage was set for Henry to show his class on 70 minutes.

Having contested Luzhny's hopeful high cross, the Frenchman pounced on a moment's indecision between Cafu and Christian Panucci as the ball bounced into space inside the penalty area to bury his shot.

Roma boss Fabio Capello, who had already brought on Vincenzo Montella, responded by introducing Gabriel Batistuta for Lima.

However, after Shaaban was called upon to make a smart save from Cafu, Henry struck again, this time with a perfectly-struck 20-yard free-kick that was curled into the top corner.

True class should, in theory, always prevail and so Henry had again proved in practice in Rome.

Teams :
Roma: Antonioli, Panucci, Candela, Cafu, Zebina , Samuel, Lima (Batistuta 73), Emerson, Cassano (Montella 64), Delvecchio (Guigou 57), Totti.

Subs Not Used: Pelizzoli, Cufre, Bombardini, Guardiola.

Booked: Samuel, Emerson, Batistuta.

Goals: Cassano 4.

Arsenal: Shaaban, Cole, Campbell, Luzhny, Cygan, Ljungberg (Edu 90), Vieira, Silva, Wiltord (Keown 84), Henry, Pires (van Bronckhorst 78).

Subs Not Used: Taylor, Jeffers, Stepanovs, Volz.

Goals: Henry 6, 70, 75.

Attendance: 70,000

Referee: L Michel (Slovakia).