Petrov pounces to maintain title push

Just six points separate Celtic from their second successive Scottish Premier League crown, after Stilian Petrov showed for the second time in a week that Kenny Dalglish's transfer acumen was not truly flawed.

Petrov was the former director of football's first signing, and, while few signs of the disastrous Dalglish-John Barnes era remain at Parkhead, the young Bulgarian is a precious inheritance for Martin O'Neill.

A carbon copy of his goal against Rangers stretched the champions' lead to 13 points. Petrov was on peanuts compared to his erstwhile colleague Eyal Berkovic, but his rich vein of form will be rewarded by an enhanced contract once the title has been officially wrapped up.

The draw at Ibrox six days earlier had, along with the bright spring sunshine, allowed a carnival spirit to descent upon the east end of Glasgow.

The knowledge that Celtic were just three wins away from the title may have set supporters' pulses racing, yet O'Neill's players were strangely unmoved. Celtic's early play was measured, if a touch flat, as they tried to tease Dundee United out of position. Had Stephen Crainey – deputising again for the injured Joos Valgaeren and earmarked for a Scotland call-up by Berti Vogts after watching him in the Old Firm derby – turned in Lubomir Moravcik's clever cut-back, then the pattern may have changed.

However, Dundee United were able to grow in confidence, playing fluently in midfield. Henrik Larsson invaded that comfort zone after 23 minutes, applying a twisting header to Steve Guppy's corner, but the goalkeeper Paul Gallacher superbly pushed the ball over the bar.

Danny Griffin, at the other end, brought a save of equal quality from Robert Douglas with a free-kick that dipped over the Celtic wall and it was left to Didier Agathe to open up the visitors with his pace.

The French winger shredded the hapless full-back, David McCracken, and, when Larsson turned a cross back into the path of Petrov in the 40th minute, few could believe that the man who scored with such poise against Rangers would mis-kick here.

Petrov's pride was clearly wounded and he atoned within a minute by breaking the deadlock. The young Bulgarian exchanged passes with Larsson to go behind United's defence and finished his burst into the box with a right-foot shot beyond Gallacher.

Larsson may be Europe's top marksman, but the Swede is blessed with much more than simply goals. His deft passing is a constant source of opportunities for others, as he demonstrated again, two minutes into the second half.

A sublime reverse pass allowed Crainey to surge into the area but the defender's cross just eluded Moravcik.

Larsson almost doubled the lead when he got in behind Griffin, but was squeezed out, before Gallacher saved a spectacular effort from Petrov.

Parkhead had witnessed a 5-1 rout on Dundee United's last visit, yet there was little sense of frustration in the 58,392 crowd, who counted down the closing minutes by acclaiming the impending championship.

The introduction of Jamie Smith for Moravcik, though, injected a new sense of vigour. The youngster's pace saw him pounce on Paul Lambert's ball over the top of the defence before rifling an angled shot against the bar. There are few other impediments, however, to Celtic's ultimate goal – the title.