Even with four of their most important players missing, the Jets’ starters put on an impressive performance this weekend in their 10-3 victory over the Lions. And on Saturday the Giants’ first team offense looked equally impressive in a 17-14 loss to the Browns.

New Jets offensive coordinator Mike Heimerdinger’s first-string offense (minus Chad Pennington, who rested his injured throwing shoulder) saw its first drive end when a Jay Fiedler pass was tipped at the line of scrimmage and intercepted. But on the next drive, the Jets manhandled the Lions’ first-string defense, capping a 16-play, 98-yard drive with a one-yard sneak by Fiedler.

Fiedler, the former Dolphins starter, is not as accurate a passer as Pennington, but he played well enough to show that another Pennington injury – or the persistence of the current one – would not necessarily be the disaster that fans fear. Fiedler used his feet well to evade the Lions’ pass rush and successfully found receivers underneath as the Lions’ secondary stayed back to prevent deep passes.

In the backfield, the Jets still need to know whether recent acquisition Derrick Blaylock, who had a pedestrian game with 21 yards on six carries, can back up Curtis Martin as well as LaMont Jordan did last season. Blaylock was an impressive backup behind Priest Holmes in Kansas City (he averaged the same 4.6 yards per carry that Martin did last season), and the Jets are counting on him this season to provide productive carries behind the 32-year-old Martin.

On defense, the Jets’ line is a concern. Jason Ferguson is now in Dallas, John Abraham is unsigned, and Dewayne Robertson is hobbled by a knee injury. But the line actually played well, with defensive end Bryan Thomas routinely beating Lions left tackle Jeff Backus when both teams had their starters in.

Thomas was a first-round pick in 2002 who has disappointed the Jets in his first three seasons, but he looked much improved against Detroit, which has to be a welcome sign for defensive coordinator Donnie Henderson in light of the question marks on the line.

The Jets’ secondary, however, showed that it needs Ty Law, who was signed last week despite ongoing recovery from January foot surgery. Rookie Justin Miller started at cornerback and struggled in coverage. Lions receiver Roy Williams had no trouble getting open against Miller, and Joey Harrington completed all nine of his passes.

Even if Law is healthy and ready to play by September, opposing third receivers could have big days against the Jets, who lack depth in the secondary. Their hopes in that regard could lie with rookie safety Kerry Rhodes, who played with the second unit and looked confident, intercepting one pass and knocking down another.

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With Ron Dayne now in Denver, no one is calling the Giants’ backfield “Thunder and Lightning.” But the moniker might be more appropriate than ever with the arrival of Brandon Jacobs.

Jacobs, a 6-foot-4 inch, 256-pound rookie from Southern Illinois, had 12 carries for 73 yards (plus an 11-yard gain on third-and-one that was negated by a holding penalty) against the Browns, showing more speed than teams expect from a back of his size.

Tiki Barber played briefly, seeing just two carries for eight yards. Like the Jets’ Martin, Barber’s durability this season will be a factor. He turned 30 in April, an age at which NFL running backs tend to decline, and he’s coming off a season with a career-high 322 carries, which means he took a lot of punishment last year.

That’s why it’s very good news for Giants fans that Jacobs played well. Seventh-year man Michael Cloud also looked good, with five carries for 58 yards. If the tandem of Jacobs and Cloud can be relied upon both to eat up yardage and reduce Barber’s workload, the Giants’ running game will take some pressure off Manning and the passing game.

Thunder and lightning had a literal effect this weekend on the Giants’ opening drive, which took 90 minutes to complete after officials sent both teams to their locker rooms after lightning struck in Cleveland. When play resumed, the Giants wrapped up a nine-play touchdown drive that covered 69 yards, with Eli Manning hitting Plaxico Burress on a well thrown 20-yard strike.

For the game, Manning looked sharp, completing six of eight passes for 53 yards in three series. The performance put to rest, at least for now, concerns that Manning and his receivers aren’t connecting and lack chemistry.

With Manning looking improved, the biggest question at quarterback becomes who will serve as his backup. Second-stringer Jesse Palmer completed two passes but had a third intercepted in brief play and was overshadowed by Tim Hasselbeck, who currently sits third on the depth chart. Hasselbeck looked more than competent in leading an 84-yard touchdown drive that included an 11-yard run for a first down and ended with a six-yard dart to receiver Ataveus Cash.

As for protection, the Browns sacked the Giants’ quarterbacks five times, but only once with Manning and the starting offensive line on the field. Part of the reason was new right tackle Kareem McKenzie, formerly of the Jets, who will be responsible this season for anchoring a notoriously weak offensive line.

On defense, Michael Strahan, now entering his 13th season, showed he’s still going strong with a sack of Browns starter Trent Dilfer. The Giants did allow Cleveland to score two touchdowns and drive for the winning field goal in the fourth quarter, but all the Browns’ scoring came after the Giants’ starters came out. New acquisition Antonio Pierce started at middle linebacker, and his presence makes the Giants’ defense more athletic and more physical.

The Jets host the Minnesota Vikings on Friday, with Pennington expected to see his first live action since the shoulder surgery that is still limiting him to light practices. The Giants host the Carolina Panthers on Saturday.

Mr. Smith writes for the statistical Web site FootballOutsiders.com.