A brace of penalties from Farrell were the only scores of a defence-dominated second half at the Sportsground, as 8/1 outsiders Connacht — inspired by man of the match Kieran Marmion — stayed in the hunt for a shock victory.
They almost got it right at the death as bodies piled in close to the Sarries line, but replacements Aly Muldowney and Paul O’Donohoe were held up short and the relieved visitors got out of Galway with the points.
This entertaining Pool 3 opener seemed to be going to script early on as converted tries from Chris Wyles and Chris Ashton saw Saracens stride into an early 14-3 lead.
United States international Wyles scorched home for the sixth-minute opener and Mark McCall’s side gave evidence of their expansive ability as backs and forwards suddenly flooded forward, including the strong-carrying Mako Vunipola, after Parks had swung over a kick for Connacht.
His front-row colleague Schalk Brits was standing wide on the right to put Ashton over for a neat finish in the corner.
Farrell’s second crisp conversion widened the gap to 11 points — just reward for Sarries’ high level of execution and the control shown by half-backs Farrell and Neil de Kock.
But their Connacht counterparts, Parks and Marmion, drove the province back into the game in the second quarter, with the hosts also tightening up their defence after some costly missed tackles.
Poolman did well to hare after a high kick and Marmion profited, collecting the ball out wide and cutting through from the left for an opportunist 18th-minute try. Parks tapping over the kick.
Sarries answered back with a long-range Farrell penalty but Connacht exerted more control nearing the break.
Their forwards grew in stature and a spell of patient build-up play was rewarded just past the hour mark when South African Danie Poolman stepped inside two defenders to score, following quick passes from John Muldoon and Marmion.
Parks converted but missed a late penalty as the sides went in all square, and Saracens regrouped to force the issue on the resumption with George Kruis and scrum-half De Kock both going close.
George Naoupu leaked a penalty near the Connacht line which allowed Farrell to boot his side back in front, but the hosts’ gritty defence continued to frustrate Sarries.
After conceding a huge amount of territory, heroic Connacht had their opportunity to build from a penalty far out and their forwards probed before Saracens won a scrum and eventually cleared.
The game remained in the balance as Farrell flicked a drop goal effort wide, however Saracens did enough to claim a tight six-point verdict in the end — the key moment seeing a Steve Borthwick-led maul set up Farrell’s match-winning penalty.
Scorers for Connacht: Tries: Marmion, Poolman. Cons: Parks 2. Pens: Parks.
Scorers for Saracens: Tries: Wyles, Ashton. Cons: Farrell 2. Pens: Farrell 3.
CONNACHT: Duffy, Carr, Henshaw, Ronaldson, Poolman, Parks, Marmion, Wilkinson, Henry, Ah You, Swift, Clarke, Muldoon, Heenan, Naoupu.
Replacements: So’oialo for Ronaldson (66), O’Donohoe for Marmion (70), Cooney for Wilkinson (70), Harris-Wright for Henry (68), O’Halloran for Swift (58), Browne for Muldoon (54).
SARACENS: Goode, Ashton, Tomkins, Wyles, Strettle, Farrell, de Kock, M Vunipola, Brits, Stevens, Borthwick, Kruis, Brown, Fraser, B Vunipola.
Replacements: Taylor for Tomkins (59), Wigglesworth for de Kock (52), George for M Vunipola (72), Gill for Stevens (72), Hargreaves for Kruis (56).
Referee: Pascal Gauzere (Fra).