By Andrew Baldock, PA Sport Rugby Union Correspondent

Henry Paul calmed England's chronic first night nerves at City of Manchester Stadium as he kept their Commonwealth Games sevens medal bid on course following two major scares.

While main tournament rivals New Zealand, Fiji and Australia breezed past inferior opponents during the opening skirmishes, England made hard work of defeating the Cook Islands and Kenya.

They trailed by seven points during the first-half of both Pool C games, before finishing on top - beating the Cook Islands 24-12 and Kenya 33-12 - to effectively secure a quarter-final place.

Coach Joe Lydon admitted that his team had received "a few wake-up calls," but was delighted to have emerged unscathed, unlike Samoa, who came spectacularly unstuck 28-20 against Kenya.

England will be certain of a last-eight spot if they avoid defeat in Saturday afternoon's final group appointment with Samoa.

But Wales marched on after they followed up a 57-7 stroll against Sri Lanka by defeating Tonga 31-10 in Pool B.

Pontypridd wing Gareth Wyatt, four-try star of the Sri Lankan romp, added another touchdown as Wales sailed into a comfortable interval lead, and there was no way back for Tonga during the second period.

But Scotland are on the verge of elimination after former Leicester wing Winston Stanley's first-half try proved enough to win a pivotal Pool A encounter.

The Scots' 7-0 defeat means that they now face a Herculean task trying to reach the knockout stages on Saturday. Only an improbable victory over competition favourites New Zealand will suffice.

Ominously though, the tournament big guns have already started flexing their muscles.

Waisale Serevi and his magical Fijians, England's possible quarter-final barrier, amassed 148 points - and conceded none - in mauling Malaysia and Trinidad and Tobago, while defending Commonwealth champions New Zealand predictably cruised unbeaten towards the knockout stages, Australia also registered a try-laden century and South Africa smashed Sri Lanka 82-0.

In comparison, England were unconvincing, but former rugby league star Paul paid tribute to the opposition, rather than highlight any home team flaws in front of a 20,000 crowd.

"I give credit to the teams that we've played against," he said. "They forced the errors, and they took advantage of them.

"Sevens is open rugby - you cannot expect to go through a tournament with no-one scoring against you."

Lydon added: "I am pleased that we won both games - they could have gone the other way.

"We have got things to work on, but we've got two wins. We didn't want to be the team on the end of an upset."

Despite parading five senior internationals, England kicked off the 16-team competition in unconvincing fashion.

It took two late Josh Lewsey tries to see them home after the unheralded Cook Islanders had threatened a colossal upset through first-half touchdowns from Amosa Amosa and Lance Fitzpatrick, which secured a 12-5 advantage.

"We made a few mistakes. If we want to progress in this tournament, then we need to eradicate them. It has brought us back to earth," said Wasps ace Lewsey,

Elsewhere, Canada fielded Fred Asselin, who was severely reprimanded by International Rugby Board chiefs earlier on Friday for using the banned substance Oxycocet in a toothache cure, while South Africa suffered an early injury blow against Tonga in Pool B, losing Springbok Gaffie Du Toit, before prevailing 26-12 and then blitzing hapless Sri Lanka.

Lydon, architect of England's rise to third place in the current world sevens rankings, fielded five internationals - Lewsey, Paul, skipper Phil Greening, Nick Duncombe and Pat Sanderson - for the tournament opener.

But with just 55 seconds gone, the Cook Islands split England's defence open for their captain Amosa to score a try that Darren Robson converted.

Trailing 7-0, England sought a rapid response, and they began dominating possession that resulted in a superb solo score by Bath flier Rob Thirlby before Fitzpatrick's try temporarily silenced the crowd of around 15,000.

A Ben Gollings try and conversion hauled England level by the break, and after some half-time words of wisdom from Lydon, Lewsey put them ahead for the first time with just three minutes remaining.

The Cook Islands went flat out for a late score, yet England had the final say through substitute Paul Sampson's brilliant running that gave Lewsey his second try, converted by Gollings.

The Kenya encounter was just as fraught, Gollings' early score being sandwiched by two Kenyan tries before Paul (2), Greening and Sampson stretched their legs and guaranteed much-needed breathing space.

But after more than five hours of action, the world sevens formbook looks like reading true with England, New Zealand, Fiji, South Africa, Australia, Wales and Canada filling seven of the quarter-final places, possibly alongside surprise packages Kenya.