diff --git a/src/cmd/go/internal/modload/buildlist.go b/src/cmd/go/internal/modload/buildlist.go
index def9c489e9..58ef80bfe5 100644
--- a/src/cmd/go/internal/modload/buildlist.go
+++ b/src/cmd/go/internal/modload/buildlist.go
@@ -11,6 +11,7 @@ import (
 	"cmd/go/internal/par"
 	"cmd/go/internal/slices"
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
@@ -758,8 +759,8 @@ func updateWorkspaceRoots(ctx context.Context, rs *Requirements, add []module.Ve
 // roots) until the set of roots has converged.
 func tidyPrunedRoots(ctx context.Context, mainModule module.Version, direct map[string]bool, pkgs []*loadPkg) (*Requirements, error) {
 	var (
-		roots        []module.Version
-		pathIncluded = map[string]bool{mainModule.Path: true}
+		roots      []module.Version
+		pathIsRoot = map[string]bool{mainModule.Path: true}
 	)
 	// We start by adding roots for every package in "all".
 	//
@@ -779,9 +780,9 @@ func tidyPrunedRoots(ctx context.Context, mainModule module.Version, direct map[
 		if !pkg.flags.has(pkgInAll) {
 			continue
 		}
-		if pkg.fromExternalModule() && !pathIncluded[pkg.mod.Path] {
+		if pkg.fromExternalModule() && !pathIsRoot[pkg.mod.Path] {
 			roots = append(roots, pkg.mod)
-			pathIncluded[pkg.mod.Path] = true
+			pathIsRoot[pkg.mod.Path] = true
 		}
 		queue = append(queue, pkg)
 		queued[pkg] = true
@@ -813,11 +814,12 @@ func tidyPrunedRoots(ctx context.Context, mainModule module.Version, direct map[
 				queue = append(queue, pkg.test)
 				queued[pkg.test] = true
 			}
-			if !pathIncluded[m.Path] {
+
+			if !pathIsRoot[m.Path] {
 				if s := mg.Selected(m.Path); cmpVersion(s, m.Version) < 0 {
 					roots = append(roots, m)
+					pathIsRoot[m.Path] = true
 				}
-				pathIncluded[m.Path] = true
 			}
 		}
 
@@ -827,10 +829,62 @@ func tidyPrunedRoots(ctx context.Context, mainModule module.Version, direct map[
 		}
 	}
 
+	roots = tidy.rootModules
 	_, err := tidy.Graph(ctx)
 	if err != nil {
 		return nil, err
 	}
+
+	// We try to avoid adding explicit requirements for test-only dependencies of
+	// packages in external modules. However, if we drop the explicit
+	// requirements, that may change an import from unambiguous (due to lazy
+	// module loading) to ambiguous (because lazy module loading no longer
+	// disambiguates it). For any package that has become ambiguous, we try
+	// to fix it by promoting its module to an explicit root.
+	// (See https://go.dev/issue/60313.)
+	q := par.NewQueue(runtime.GOMAXPROCS(0))
+	for {
+		var disambiguateRoot sync.Map
+		for _, pkg := range pkgs {
+			if pkg.mod.Path == "" || pathIsRoot[pkg.mod.Path] {
+				// Lazy module loading will cause m to be checked before any other modules
+				// that are only indirectly required. It is as unambiguous as possible.
+				continue
+			}
+			pkg := pkg
+			q.Add(func() {
+				skipModFile := true
+				_, _, _, _, err := importFromModules(ctx, pkg.path, tidy, nil, skipModFile)
+				if aie := (*AmbiguousImportError)(nil); errors.As(err, &aie) {
+					disambiguateRoot.Store(pkg.mod, true)
+				}
+			})
+		}
+		<-q.Idle()
+
+		disambiguateRoot.Range(func(k, _ any) bool {
+			m := k.(module.Version)
+			roots = append(roots, m)
+			pathIsRoot[m.Path] = true
+			return true
+		})
+
+		if len(roots) > len(tidy.rootModules) {
+			module.Sort(roots)
+			tidy = newRequirements(pruned, roots, tidy.direct)
+			_, err = tidy.Graph(ctx)
+			if err != nil {
+				return nil, err
+			}
+			// Adding these roots may have pulled additional modules into the module
+			// graph, causing additional packages to become ambiguous. Keep iterating
+			// until we reach a fixed point.
+			continue
+		}
+
+		break
+	}
+
 	return tidy, nil
 }
 
diff --git a/src/cmd/go/testdata/script/mod_tidy_issue60313.txt b/src/cmd/go/testdata/script/mod_tidy_issue60313.txt
index 1ae2c13b74..cd704ce34c 100644
--- a/src/cmd/go/testdata/script/mod_tidy_issue60313.txt
+++ b/src/cmd/go/testdata/script/mod_tidy_issue60313.txt
@@ -2,12 +2,9 @@
 # dependencies needed to prevent 'ambiguous import' errors in external test
 # dependencies.
 
+cp go.mod go.mod.orig
 go mod tidy
-cp go.mod tidy1.mod
-
-! go mod tidy  # BUG: This should succeed and leave go.mod unchanged.
-	# cmp go.mod tidy1.mod
-stderr 'ambiguous import'
+cmp go.mod go.mod.orig
 
 -- go.mod --
 module example