Given Bohemians’ relatively light workload in recent weeks, in contrast with their cross-city rivals, an early home onslaught was expected but it was Rovers who showed the greater attacking intent throughout with Twigg directing a ninth-minute header too close to Barry Murphy following Dean Kelly’s precise cross.
Enda Stevens and Billy Dennehy combined well down the visitors’ left flank and in the 20th minute Dennehy collected Ronan Finn’s pass to centre for Twigg, who shot wastefully wide.
A second-minute cross-shot by Christy Fagan, following a misplaced Finn pass, was Bohs’ sole attacking foray in the opening quarter, with the lone-striker lacking conviction as he shot wide.
Conversely, the champions were able to offer Twigg far greater support and Kelly should have opened the scoring in the 26th minute but his far-post header from Stevens’ sublime cross crashed off the crossbar with Stephen Rice hammering the rebound over from 10 yards.
Despite enjoying an abundance of possession, the Hoops struggled to create clear-cut chances as the half progressed, although Dennehy could have done better in injury-time when, after cutting inside Heary, he placed a weak right-foot shot too close to Murphy.
The second half resumed in a similar vein with Murphy once again called into action when tipping over a Craig Sives header as the centre-half was left unmarked following a Gary McCormack free-kick in the 50th minute.
However, there was little that Murphy could do to prevent his side falling behind in the 66th minute as Kelly and Twigg rose together to meet a Dennehy corner-kick, with the latter’s deflection from eight yards taking the ball beyond the wrong-footed keeper.
The hosts, enlivened by the pace of substitute Aidan Downes, strived in vain for an equaliser with Ger O’Brien spurning their best chance within two minutes, blazing over the bar following a terrific Downes run and cross.
O’Brien almost made amends in injury-time but his close-range header from a Downes cross lacked accuracy as Rovers held on.
With the three points secured, Shamrock Rovers manager Michael O’Neill was happy to offer his thoughts on the prospect of facing Partizan Belgrade in their Europa League qualifier, starting with a home tie on Monday week.
He said: “Being an unseeded side, it was always going to be difficult, no matter who we drew. We could have had the glamour tie with Atletico Madrid but Partizan will be a top side. Their season hasn’t started, however, so that may be of advantage to us.’’
BOHEMIANS: Murphy; Heary, Burns, Price, Rossiter (Cahill 59); Buckley, O’Brien, Cronin, Bayly (Downes 59), Brennan; Fagan (Forrester 84).
SHAMROCK ROVERS: Thompson; Flynn, Sives, Murray, Stevens; Kelly, McCormack, Rice, Finn (O’Neill 75), Dennehy (Moore 87); Twigg (Kilduff, 90).
Referee: Damien Hancock (Dublin).