Ramires brace boosts Chelsea
The Brazil midfielder netted either side of an own goal and Frank Lampard added a late fourth as Jose Mourinho's side made amends for the round one loss to Basle and last season's Europa League defeat at the home of the Romanian champions, despite the early departure of striker Fernando Torres with a knee injury.
Torres, who earlier on Tuesday received a Football Association disciplinary reprieve following his altercation with Tottenham defender Jan Vertonghen, started for a third successive game but lasted just 11 minutes before being substituted after failing to shake off a blow to his left knee.
His replacement Samuel Eto'o had a role in the opening goal, weakly helping on Andre Schurrle's cross for Ramires to prod the ball in. A strong run from Eto'o, following Juan Mata's incisive pass, then saw the hapless Daniel Georgievski divert the ball into his own net to give the visitors a 2-0 half-time lead.
A roof covered the pitch from the incessant torrential rain, but Steaua were struggling to protect themselves from wave after wave of Chelsea attacks. Ramires, who was excellent throughout, now has three goals in three games after finishing off a flowing move for his second of the night and Chelsea's third and Lampard netted a fourth in stoppage time.
Mata, who hit the post in the second half, fully justified his inclusion and Andre Schurrle was a constant menace, but encountered little resistance from his opposite number Georgievski.
Chelsea next play Schalke twice, the first contest in Gelsenkirchen in three weeks' time, after claiming a second away win of the season. The first was at Swindon in the Capital One Cup and the Blues will chase another at Norwich in the Barclays Premier League on Sunday.
After being spared further censure from the FA, Torres started alongside fellow World Cup winner Mata, who was one of two changes from the side which began at Tottenham after impressing Mourinho. It was Mata's fourth start of a season he has begun as a peripheral figure and the Spaniard was initially deployed in his favored central playmaker role, with Oscar on the right wing and Schurrle, the second change, on the left in place of Eden Hazard (ankle).
Chelsea made early inroads, particularly down their left and Schurrle hit two tame early efforts before Torres departed. The loss of Torres did little to disrupt Chelsea, who took the lead after Ramires won the ball inside his own half and found Schurrle, who darted round Georgievski and sent in a cross.
Eto'o could only help it on and Ramires, who had continued his run, got the decisive touch to beat Ciprian Tatarusanu. Chelsea had the majority of possession, but there were too many lapses and losses of concentration for the men in white to be comfortable.
Petr Cech had to race 20 yards out of his area and slide to meet a mis-hit Oscar pass towards John Terry as Federico Piovaccari threatened to run through. Chelsea claimed a second when Ashley Cole found Mata, who played the ball first time to Eto'o.
The striker surged towards goal and saw his shot saved by Tatarusanu, but the ball ricocheted in off Georgievski. Steaua attempted to respond and Nicolae Stanciu shot wide before the interval, but it was Chelsea who resumed on the attack.
Ten minutes into the second half Chelsea had a third. Schurrle again ran at the Steaua defense, centered for Oscar, who played the ball on for Ramires to emphatically blast it into the roof of the net.
Mata hit the post soon afterwards before Cech crashed into the upright when tipping over Cristian Tanase's chip, leaving the goalkeeper needing treatment. The Steaua defence was making Schurrle look good, but the Germany international showed there is plenty of room for improvement.
First he shot weakly at Tatarusanu and then he fired wide when he had time to pick his spot after being found by Ramires. Georgievski was put out of his misery and replaced with 20 minutes remaining, but the damage was already done.
Chelsea were home and - in a city where the rain has fallen since their arrival - dry, but still showed signs of fragility. Cech saved from Stanciu, who blasted the rebound over, and Lampard blocked from Lucian Filip following a corner.
The midfielder then found himself in more familiar territory and netted at the other end following a pass from substitute Willian.