DENVER (AP) — Ron Dayne spent the Denver Broncos’ first game in street clothes and most of the second on the sideline. By the end on Sunday, though, he was the key in helping Denver to the winning score — Jason Elam’s 41-yard field goal with 5 seconds left — in their come-from-behind 20-17 victory over the San Diego Chargers. Dayne came off the bench and ran six times for 39 yards on the winning drive, including an 11-yard gain on fourth-and-1 from the Chargers 33. It was the most clutch NFL performance for the Heisman Trophy winner, who came to Denver after five disappointing seasons with the Giants. It also saved the Broncos (1-1) from going 0-2 for the first time since 1999. Instead, it’s San Diego (0-2) that remains winless despite leading 14-3 early and turning the sellout crowd at Invesco Field squarely against the home team. LaDainian Tomlinson ran for both San Diego scores in the second quarter. The first gave Tomlinson the NFL record with a rushing touchdown in 14 straight games. The second gave the Chargers a 14-3 lead and a few minutes later, the Broncos headed into halftime being showered by boos after a particularly inept half on offense. Their rally started on the first play from scrimmage in the third quarter, when Champ Bailey stepped in front of Keenan McCardell, picked off Drew Brees’ pass and went in untouched for a 25-yard score. Defense and special teams kept the Broncos in great field position through the quarter, but the offense struggled and Elam missed a pair of 53-yard field-goal attempts. Midway in the fourth quarter, Broncos rookie Darrent Williams burst through untouched on a punt return for what looked like a touchdown. But the Broncos were penalized for too many men on the field, the result of a number of players running off the sideline to celebrate before Williams hit the end zone. The Broncos staved off major embarrassment by scoring on that drive to go ahead 17-14 and the Chargers answered back with a field goal — their only decent drive of the second half — that tied the score and set things up for Dayne. He was viewed as a longshot to make the roster, almost an afterthought in a training camp that included Maurice Clarett and Jerry Rice. And even when Dayne made the team, questions persisted when coach Mike Shanahan made him inactive for Denver’s 34-10 loss to Miami on opening day. On Sunday, though, he was suited up and did some damage after spending most of the game watching Mike Anderson get bottled up, held to 49 yards on 15 carries. Jake Plummer had decent stats — 23-for-37 for 248 yards — but penalties and turnovers short-circuited a number of Denver drives and the frustration built up inside of Invesco Field. Besides Dayne, it was defense and special teams that won it for the Broncos. Denver held Brees to 175 yards, Tomlinson to 52 yards rushing and no receptions and the Chargers offense to only 41 yards of offense in the second half.