Ortiz, mired in an early season slump that had him yanked from the DH spot the previous two games, hit his first homer of the season in the Red Sox's 4-3 win over the Baltimore Orioles on Friday night.
"You can tell he's getting a lot better," said Martinez, who joined the Red Sox in a trade-deadline deal last season. "You can see it in his [batting practice]."
The rest of Ortiz's teammates can only hope Martinez is right.
"He's huge [for us]," Bill Hall said. "A guy with that kind of ability and talent. We know what he can do."
Boston won its third in four games after a five-game losing streak. The Red Sox were 16-2 against the Orioles in 2009, winning the final eight meetings.
"We're winning ugly, but we're finding ways to win" Boston second baseman Dustin Pedroia said.
Adam Jones had a two-run homer for Baltimore, which overcame a 3-0 deficit but dropped to a major league-worst 2-15 this season.
The Red Sox loaded the bases with a single and two walks against two relievers in the eighth before Beltre took Johnson's 3-1 pitch inside for the go-ahead run. Matt Albers (0-2) gave up J.D. Drew's leadoff single before retiring the next two batters. Will Ohman walked Martinez intentionally before walking Ortiz on four pitches.
"Walks obviously played a pivotal role in the game," Baltimore manager Dave Trembley said. "The walk to Ortiz turned out to be the key one."
Manny Delcarmen (1-1) got the win despite allowing an inherited runner to score in the eighth. Jonathan Papelbon got Julio Lugo to strike out with runners on first and second to end it for his fourth save.
The Orioles didn't make any excuses on how they gave it away in the eighth.
"You can't do that at the end of a game," Johnson said. "I'm trying to throw the ball down the middle of the plate and it's not going there. You can't defend the walk. That's the worst thing that can happen."
Boston starter Jon Lester worked out of three jams, but left in the sixth inning with a 3-0 lead. He remained unbeaten in 13 career starts against Baltimore, 10-0 with a 2.22 ERA.
"He was pitching great, a couple of tough innings" Boston manager Terry Francona said.
The Red Sox added runs in the third and fifth to open a 3-0 edge.
Drew's sacrifice fly made it 2-0 in the third.
Beltre singled leading off the fifth, advanced on Jeremy Hermida's infield hit and went to third on the same play when third baseman Miguel Tejada threw the ball into short right. He then scored on Josh Reddick's double-play grounder.
Jones' two-run homer off Bard made it 3-2 in the seventh.
Matt Wieters doubled against Hideki Okajima leading off the eighth and former Red Sox shortstop Lugo pinch ran. Delcarmen entered and walked Nolan Reimold before Garrett Atkins, who ended two innings with the bases loaded, bunted into a fielder's choice -- with a close play at second. Pinch hitter Luke Scott's slow roller to second scored Lugo, tying it 3-all.
Atkins took a called third strike against Lester in the fourth and popped to center off reliever Daniel Bard in the sixth.
Guthrie gave up three runs, five hits, walked two without a strikeout in six innings. He's allowed three runs or less in each of his four starts.
Francona said before the game that RHP Daisuke Matsuzaka is scheduled to throw a four-inning simulated game in Toronto on Monday and will start in Baltimore next weekend. ... Francona said that the day off "was good mentally" for Ortiz. ... Tejada made two errors. ... Jones was 0 for 15 before his homer. ... Boston's bullpen had gone 19 2/3 scoreless innings before Jones' homer. ... The Red Sox are 20-2 against Baltimore since Sept. 1, 2008.